<ver0.2>大数计算加减乘除的字符实现
借着假期，把乘法和除法做完了，乘法用加法实现，除法用减法实现。这回四则运算都齐了，打算到此为止。本来想的很简单的，结果函数越写越长，很多代码是重复的就直接复制了，没把程序结构处理好，看上去乱糟糟的。欢迎大家找茬。
加减乘除全部采用搬运字符的方法实现，即'1' + '2' 得'3'，不是转换成数字后计算，用基本的C代码，不依赖任何库，gcc和g++都可以编译（测试部分除外）。
贴上全部函数的完整代码：
#include <stdio.h>
int dec_char_add(char in_carry, char c1, char c2, char * out_carry, char * result);
/* dec_char_add() return 1 if no error, otherwise 0
*
* c1 ['0'-'9'] '6'
* + c2 ['0'-'9'] + '8'
* + in_carry ['0'-'1'] + '1'
* _________________________________________ ________________
* = out_carry result = '1' '5'
* ['0'-'1'] ['0'-'9']
*/
int dec_char_sub(char in_borrow, char c1, char c2, char * out_borrow, char * result);
/* dec_char_sub() return 1 if no error, otherwise 0
*
* ['0'-'1']
* out_borrow c1 ['0'-'9'] '1' '6' '0' '6'
* - c2 ['0'-'9'] - '8' - '2'
* - in_borrow ['0'-'1'] - '1' - '1'
* _________________________________________ ________________ ________________
* = result = '7' = '3'
* ['0'-'9']
*/
int is_dec_str(char * str, int * p_or_n, int * i_qty, int * d_qty, int * dot_pos);
/* is_dec_str() return 1 if Yes, otherwise 0
* Check str if a valid decimal number or not. Return 1 if Yes, or 0 if No.
* str: the string to be checked.
* p_or_n: indicate the number is positive (1) or negative (-1) (after check).
* i_qty: integeral part char qty (length)
* d_qty: decimal part char qty (length)
* dot_pos: return position of '.', (or '\0' if no '.'), of the str
* eg: if p_or_n = -1, i_qty = 5, d_qty = 2, dot_pos = 6 str may look like -nnnnn.nn
*/
int add_ip_dp(char * str1, int dot_pos1, int i_qty1, int d_qty1,
char * str2, int dot_pos2, int i_qty2, int d_qty2,
char * str3, int str3_array_size, int * offset);
/*add_ip_dp() return 1 if no error, otherwise 0
*add integral part and decimal part (str3 = str1 + str2)
*dot_pos: index of str where '.' located for decimal number
* or '\0' located for integral number.
* i_qty: integral number quantity (integral part length)
* d_qty: decimal number quantity (decimal part length)
* str3: array to store result
* str3_array_size: array size
* offset: result will start from here (this function write result from tail to head)
*/
int sub_ip_dp(char * str1, int dot_pos1, int i_qty1, int d_qty1,
char * str2, int dot_pos2, int i_qty2, int d_qty2,
char * str3, int str3_array_size, int * offset);
/*sub_ip_dp() return 1 if no error, -1 if sub error (str1 < str2), 0 if other errors.
*sub integral part and decimal part (str3 = str1 - str2)
*dot_pos: index of str where '.' located for decimal number
* or '\0' located for integral number.
* i_qty: integral number quantity (integral part length)
* d_qty: decimal number quantity (decimal part length)
* str3: array to store result
* str3_array_size: array size
* offset: result will start from here (this function write result from tail to head)
*/
int dec_str_add(char * str1, char * str2, char * str3, int str3_array_size, int * offset);
/* dec_str_add() return 1 if no error, otherwise 0
*add decimal strings (str3 = str1 + str2)
* str3: array to store result
* str3_array_size: array size
* offset: result will start from here (this function write result from tail to head)
* better to have big size for str3,
* at least +2 more than total length of str1 and str2 is suggested.
*/
int dec_str_sub(char * str1, char * str2, char * str3, int str3_array_size, int * offset);
/* dec_str_sub() return 1 if no error, otherwise 0
*sub decimal strings (str3 = str1 - str2)
* str3: array to store result
* str3_array_size: array size
* offset: result will start from here (this function write result from tail to head)
* better to have big size for str3,
* at least +2 more than total length of str1 and str2 is suggested.
*/
int add_up_str(char * s1, int * h, int * t, char * s2, int ls2, int s);
/*add_up_str() return 1 if no error, otherwise 0
*str1 += str2
* ****************369258147'\0'
* ^ ^ ^
* s1 h t h = head, t = tail
* |
* + 456789'\0' | ls2 = length of s2
* ^ | | ('\0' not counted)
* s2 | |
* |<----|
* s s = shift to left (negative value)
* ________________________________________
*
* = *************457158258147'\0'
* ^ ^ ^
* s1 h t
*
*/
int sub_off_str(char * s1, int * h, int * t, char * s2, int ls2, int s);
/*sub_off_str() return 1 if no error, -1 if sub error (str1 < str2), 0 if other errors.
*str1 -= str2
* *************457158258147'\0'
* ^ ^ ^
* s1 h t h = head, t = tail
* |
* - 456789'\0' | ls2 = length of s2
* ^ | | ('\0' not counted)
* s2 | |
* |<----|
* s s = shift to left (negative value)
* ________________________________________
*
* = ****************369258147'\0'
* ^ ^ ^
* s1 h t
*/
int sub_off_str_chk(char * s1, int * h, int * t, char * s2, int ls2, int s);
/*sub_off_str_chk() is almost same as sub_off_str()
*it will try to calulate and check if "borrow" happen (s1 < s2)
*keeps no change of s1, and also h and t.
*/
int dec_str_mul(char * str1, char * str2, char * str3, int str3_array_size, int * offset);
/* dec_str_mul() return 1 if no error, otherwise 0
*mul decimal strings (str3 = str1 * str2)
* str3: array to store result
* str3_array_size: array size
* offset: result will start from here (this function write result from tail to head)
* better to have big size for str3,
* at least (+2 more than total length of str1 and str2) * 2 is suggested.
*/
int dec_str_div(char * str1, char * str2, char * str3,
int str3_array_size, int max_decimal_len, int * offset);
/* dec_str_mul() return 1 if no error, otherwise 0
* div decimal strings (str3 = str1 / str2)
*str3: array to store result
*str3_array_size: array size
*max_decimal_len: the max length of decimal parts should kept
* eg: 20 keep 20 decimal parts
* eg: 0 keep no decimal parts
* eg: -1 calculate unitl the end of str3_array_size.
* offset: result will start from here
* better to have big size for str3,
* at least (+2 more than total length of str1 and str2) * 4 is suggested.
*/
int main(void) //testing
{
const int ArrSize = 1024; //accept length of chars during test.
char str1;
char str2;
char str3;
int index, r;
printf("Enter 1st number: ");
fgets(str1, ArrSize, stdin);
for (int i = 0; i < ArrSize; i++)
{
if (str1 == '\n')
{
str1 = '\0';
break;
}
}
printf("Enter 2nd number: ");
fgets(str2, ArrSize, stdin);
for (int i = 0; i < ArrSize; i++)
{
if (str2 == '\n')
{
str2 = '\0';
break;
}
}
r = dec_str_add(str1, str2, str3, ArrSize * 4, &index);
printf("return from dec_str_add() is %d\n", r);
printf(" %s + %s \n = %s\n", str1, str2, str3 + index);
r = dec_str_sub(str1, str2, str3, ArrSize * 4, &index);
printf("return from dec_str_sub() is %d\n", r);
printf(" %s - %s \n = %s\n", str1, str2, str3 + index);
r = dec_str_mul(str1, str2, str3, ArrSize * 4, &index);
printf("return from dec_str_mul() is %d\n", r);
printf(" %s * %s \n = %s\n", str1, str2, str3 + index);
r = dec_str_div(str1, str2, str3, ArrSize * 4, -1, &index);
printf("return from dec_str_div() is %d\n", r);
printf(" %s / %s \n = %s\n", str1, str2, str3 + index);
return 0;
}
int dec_str_div(char * str1, char * str2, char * str3,
int str3_array_size, int max_decimal_len, int * offset)
{
int pn1, pn2; //indicate positive or negative for str1 and str2.
int iq1, iq2; //store integral part quantity for str1 and str2.
int dq1, dq2; //store decimal part quantity for str1 and str2.
int dp1, dp2; //store '.' position for str1 and str2.
int rt1, rt2, rt3; //temp return value;
int i, j; //i and j are temp index
int q; //q is a temp quantity
char * s1; //s1 is a copy of str1 without '.'
char * s2; //s2 is a copy of str2 without '.'
int l1, l2; //l1 and l2 is length of s1 and s2 ('\0' not counted).
int h1, t1; //h1 and t1 are both index to head and tail of valid chars in s1
char * s3; //s3 = s1 / s2
int s3_array_size; //s3 array size
int sft; //sft is shift
int h, t; //h and t are both index to head and tail of valid chars in s3
int d; //d is a index to dot position in s3
int w; //w is a position to write in s3
char ch; //ch is a temp char
char carry; //carry is a temp carry
char result_ch; //result_ch is a temp result char
int moved_remainder_tail; //this index is same value as l2, otherwise wrong
rt1 = is_dec_str(str1, &pn1, &iq1, &dq1, &dp1);
if (rt1 == 0)
return 0; //Error: str1 is not a number.
rt2 = is_dec_str(str2, &pn2, &iq2, &dq2, &dp2);
if (rt2 == 0)
return 0; //Error: str2 is not a number.
//divisor should not be zero, check if str2 is zero or not
if (iq2 + dq2 == 1)
{
if (iq2 == 1 && str2 == '0')
return 0; //Error: str2 is "0"
if (dq2 == 1 && str2 == '0')
return 0; //Error: str2 is ".0"
}
//copy valid chars of str1 to store in the begining of str3 (without '.')
s1 = str3;
i = iq1;
j = 0;
while (i > 0)
s1 = str1; //copy integral parts
i = 1;
while (i <= dq1)
s1 = str1; //copy decimal parts
s1 = '\0'; //add '\0' in the end of string.
l1 = j; //l1 = strlen(s1)
//add '0' at tail of s1 if needed (s1 and s2 are both enlarged until no '.')
if (dq1 < dq2)
{
q = dq2 - dq1;
for (i = 0; i < q; i++)
s1 = '0';
s1 = '\0';
}
//remove beginning '0' in s1, recalculate l1
if (s1 == '0' && l1 > 1)
{
i = 0;
j = 0;
while (s1 == '0')
i++; //i is an index first char of not '0'
if (s1 == '\0')
{ //looks like "0000000"
s1 = '\0';
l1 = 1;
}
else
{ //looks like "0000066"
while (s1 != '\0')
s1 = s1;
s1 = '\0';
l1 = j;
}
}
//copy valid chars of str2 to store in str3 (after s1) (without '.')
s2 = s1 + (l1 + 1);
i = iq2;
j = 0;
while (i > 0)
s2 = str2; //copy integral parts
i = 1;
while (i <= dq2)
s2 = str2; //copy decimal parts
s2 = '\0'; //add '\0' in the end of string.
l2 = j; //l2 = strlen(s2)
//add '0' at tail of s2 if needed (s1 and s2 are both enlarged until no '.')
if (dq2 < dq1)
{
q = dq1 - dq2;
for (i = 0; i < q; i++)
s2 = '0';
s2 = '\0';
}
//remove beginning '0' in s2, recalculate l2
if (s2 == '0' && l2 > 1)
{
i = 0;
j = 0;
while (s2 == '0')
i++; //i is an index first char of not '0'
if (s2 == '\0')
{ //looks like "0000000"
s2 = '\0';
l2 = 1;
}
else
{ //looks like "0000066"
while (s2 != '\0')
s2 = s2;
s2 = '\0';
l2 = j;
}
}
//enlarge space for s1, need more space to be a dividend
h1 = 0; //head of s1 before enlarge
t1 = l1 - 1; //tail of s1 before enlarge
q = (str3_array_size - (l2 + 1)) / 2; //expected size
if (q < (l1 + 1))
return 0; //Error: no enough space in str3
q = q - (l1 + 1); //quantity of space to move backward
i = l1 + 1 + l2 + 1; //current index of s2 end
j = i + q; //new index of s2 end
while (i >= 0)
str3 = str3; //move backward for s1 and s2.
h1 += q;
t1 += q;
l1 += q;
s2 += q;
//divide s1 by s2, store result in s3 (after s2), step 1, initial s3.
s3 = s2 + (l2 + 1);
s3_array_size = str3_array_size - (l1 + 1) - (l2 + 1);
d = -1; //dot position set an inpossible value.
//divide s1 by s2, store result in s3 (after s2), step 2, calc integeral parts.
i = t1 - h1 + 1 - l2; //i is a shift now (length of s1 - length of s2)
w = 1; //write result to: start from s3, leave s3 for negative simbol if need
h = w;
if (i < 0)
{
s3 = '0';
t = w;
w++;
}
for ( ; i >= 0; --i)
{
if (h1 == t1 && h1 == '0')
s3 = '0'; //remainder is '0', directly fill '0' instead calculate.
else
{
ch = '0';
carry = '0';
while (-1 != sub_off_str_chk(s1, &h1, &t1, s2, l2, -i))
{
rt3 = sub_off_str(s1, &h1, &t1, s2, l2, -i);
if (rt3 == 0)
return 0; //Error: something wrong.
rt3 = dec_char_add(carry, ch, '1', &carry, &result_ch); //ch++
if (rt3 == 0)
return 0; //Error: something wrong.
ch = result_ch;
if (carry == '1')
return 0; //Error: something wrong.
if (ch == '9')
break; //finish: successfully looped 9 times, don't loop more
}
s3 = ch;
}
t = w;
w++;
}
if (h1 == t1 && s1 == '0') //if no remainders.
max_decimal_len = 0; //set it to 0 will skip step 3 to 5
//divide s1 by s2, store result in s3 (after s2), step 3, put a '.' in s3.
if (max_decimal_len != 0)
{
d = w; //record dot position of s3
s3 = '.';
t = w;
w++;
}
//divide s1 by s2, store result in s3 (after s2), step 4, move s1 remainders to front.
if (max_decimal_len != 0)
{
moved_remainder_tail = (l2 > (t1 - h1 + 1)) ? l2 : (t1 - h1 + 1);
i = t1;
j = moved_remainder_tail;
while (i >= h1) //moving s1
s1 = s1;
h1 = ++j; //note: h1 is certainly >= 1
for (i = moved_remainder_tail + 1; i <= t1; i++)
s1 = '0'; //fill '0' following s1 remainders
}
//divide s1 by s2, store result in s3 (after s2), step 5, calc decimal parts.
if (max_decimal_len != 0)
{
i = t1 - (moved_remainder_tail + 1); //i is a shift, + 1 means first decimal part
if (i < 0) //impossible
{
s3 = '0';
t = w;
w++;
}
for ( ; i >= 0; --i)
{
if (h1 == t1 && h1 == '0')
break; //stop now, remainder is '0', no need continue for decimal parts.
ch = '0';
carry = '0';
while (-1 != sub_off_str_chk(s1, &h1, &t1, s2, l2, -i))
{
rt3 = sub_off_str(s1, &h1, &t1, s2, l2, -i);
if (rt3 == 0)
return 0; //Error: something wrong.
rt3 = dec_char_add(carry, ch, '1', &carry, &result_ch); //ch++
if (rt3 == 0)
return 0; //Error: something wrong.
ch = result_ch;
if (carry == '1')
return 0; //Error: something wrong.
if (ch == '9')
break; //finish: successfully looped 9 times, don't loop more
}
s3 = ch;
t = w;
w++;
if (w == s3_array_size - 1)
break; //one char space left. finish now.(last space for '\0')
if (w > s3_array_size - 1)
break; //impossible
if (max_decimal_len != -1)
{
if (t - d == max_decimal_len)
break; //finish now
if (t - d > max_decimal_len)
break; //impossible
}
}
}
//divide s1 by s2, store result in s3 (after s2), step 5, remove excessive '0' in s3.
if (d == -1) //s3 is an integer, dot position had not been set
d = t + 1; //set it at the end of s3 string.
while (s3 == '0' && d - h > 1) //remove '0' at front of integeral parts
h++;
while (s3 == '0' && t - d > 0) //remove '0' at end of decimal parts
t--;
if (s3 == '.') //all decimal parts are '0' and have been removed
t--;
//divide s1 by s2, store result in s3 (after s2), step 6, write '\0' in the end of s3.
s3 = '\0';
//insert '-' for s3 if applicable
if (pn1 * pn2 == -1)
{
if (s3 == '0' && s3 == '\0')
; //it's 0, do nothing
else
{
i = h;
if (--i < 0)
return 0; //Error: no enough space in s3
s3 = '-';
h = i;
}
}
//caculate result offset for str3.
*offset = h + (l1 + 1) + (l2 + 1);
return 1;
}
int dec_str_mul(char * str1, char * str2, char * str3, int str3_array_size, int * offset)
{
int pn1, pn2; //indicate positive or negative for str1 and str2.
int iq1, iq2; //store integral part quantity for str1 and str2.
int dq1, dq2; //store decimal part quantity for str1 and str2.
int dp1, dp2; //store '.' position for str1 and str2.
int rt1, rt2, rt3; //temp return value;
int i, j; //i and j are temp index
char * s1; //s1 is a copy of str1 without '.'
char * s2; //s2 is a copy of str2 without '.'
int l1, l2; //l1 and l2 is length of s1 and s2 ('\0' not counted).
char * s3; //s3 = s1 * s2
int s3_array_size; //s3 array size
int h, t; //h and t are both index to head and tail of valid chars in s3
char ch; //ch is a temp char
char carry; //carry is a temp carry
char result_ch; //result_ch is a temp result char
rt1 = is_dec_str(str1, &pn1, &iq1, &dq1, &dp1);
if (rt1 == 0)
return 0; //Error: str1 is not a number.
rt2 = is_dec_str(str2, &pn2, &iq2, &dq2, &dp2);
if (rt2 == 0)
return 0; //Error: str2 is not a number.
//copy valid chars of str1 to store in the begining of str3 (without '.')
s1 = str3;
i = iq1;
j = 0;
while (i > 0)
s1 = str1; //copy integral parts
i = 1;
while (i <= dq1)
s1 = str1; //copy decimal parts
s1 = '\0'; //add '\0' in the end of string.
l1 = j; //l1 = strlen(s1)
//remove beginning '0' in s1, recalculate l1
if (s1 == '0' && l1 > 1)
{
i = 0;
j = 0;
while (s1 == '0')
i++; //i is an index first char of not '0'
if (s1 == '\0')
{ //looks like "0000000"
s1 = '\0';
l1 = 1;
}
else
{ //looks like "0000066"
while (s1 != '\0')
s1 = s1;
s1 = '\0';
l1 = j;
}
}
//copy valid chars of str2 to store in str3 (after s1) (without '.')
s2 = s1 + (l1 + 1);
i = iq2;
j = 0;
while (i > 0)
s2 = str2; //copy integral parts
i = 1;
while (i <= dq2)
s2 = str2; //copy decimal parts
s2 = '\0'; //add '\0' in the end of string.
l2 = j; //l2 = strlen(s2)
//remove beginning '0' in s2, recalculate l2
if (s2 == '0' && l2 > 1)
{
i = 0;
j = 0;
while (s2 == '0')
i++; //i is an index first char of not '0'
if (s2 == '\0')
{ //looks like "0000000"
s2 = '\0';
l2 = 1;
}
else
{ //looks like "0000066"
while (s2 != '\0')
s2 = s2;
s2 = '\0';
l2 = j;
}
}
//multiply s1 and s2, store result in s3 (after s2)
s3 = s2 + (l2 + 1);
s3_array_size = str3_array_size - (l1 + 1) - (l2 + 1);
t = s3_array_size - 1;//t now point to the last item of array.
s3 = '\0'; //notice: leave 2 '\0' at the end of s3.
s3 = '\0';
s3 = '0'; //s3 initialed as value of '0'
h = t;
for (i = 0; i < l2; i++) //loop every char of s2
{
j = l2 - 1 - i; //index of s2 (from tail to head)
ch = '0'; //ch is a temp char
carry = '0'; //carry is a temp carry
while (s2 != ch)
{
rt3 = add_up_str(s3, &h, &t, s1, l1, -i); //s1 * s2
if (rt3 == 0)
return 0; //Error: something wrong.
rt3 = dec_char_add(carry, ch, '1', &carry, &result_ch); //ch++
if (rt3 == 0)
return 0; //Error: something wrong.
ch = result_ch;
if (carry == '1')
return 0; //Error: something wrong.
}
}
//insert '.' for s3 if applicable
if (dq1 + dq2 != 0)
{
i = dq1 + dq2;
j = t;
while (i > 0)
{
s3 = s3; //don't worry, remember, s3 has 2 '\0' in the end.
j--;
i--;
if (j < h) //oh, you should fill '0' in the front
{
if (--h < 0)
return 0; //Error: no enough space in s3
s3 = '0';
}
}
s3 = '.';
t++;
}
//remove ending '0' in the decimal part of s3
if (dq1 + dq2 != 0)
{
while (s3 == '0')
s3 = '\0';
}
//remove ending '.' if s3 end with '.'
if (s3 == '.')
s3 = '\0';
//remove excessive '0' in the front of integeral parts
while (s3 == '0')
h++;
if (s3 == '\0' || s3 == '.')
{
if (--h < 0)
return 0; //Error: no enough space in s3
s3 = '0';
}
//insert '-' for s3 if applicable
if (pn1 * pn2 == -1)
{
if (s3 == '0' && s3 == '\0')
; //it's 0, do nothing
else
{
i = h;
if (--i < 0)
return 0; //Error: no enough space in s3
s3 = '-';
h = i;
}
}
//caculate result offset for str3.
*offset = h + (l1 + 1) + (l2 + 1);
return 1;
}
int sub_off_str_chk(char * s1, int * h, int * t, char * s2, int ls2, int s)
{
int yh = *h; // yh = copy of *h
int yt = *t; // yt = copy of *t
int i1 = yt + s; // i1 is char index of s1
int i2 = ls2 - 1; // i2 is char index of s2
char borrow = '0'; // borrow is a borrow
char c1, c2, c3; // c1, c2 and c3 are temp chars
while (i2 >= 0) // loop from the tail char to the head char of s2
{
if (i1 < 0) // Error: not enough space in s1
return 0;
while (i1 < yh) // fill '0' before s1 if necessary
{
--(yh);
if (yh < 0) // Error: not enough space in s1
return 0;
s1 = '0';
}
c1 = s1;
c2 = s2;
if (0 == dec_char_sub(borrow, c1, c2, &borrow, &c3))
return 0; // Error: return error from dec_char_sub()
// s1 = c3; // no write back, check only.
--i1;
--i2;
}
while (borrow == '1')// continue with i1: loop until borrow =='0'
{
if (i1 < 0) // Error: not enough space in s1
return 0;
if (i1 < yh) // Error: s1 < s2
return -1;
c1 = s1;
c2 = '0';
if (0 == dec_char_sub(borrow, c1, c2, &borrow, &c3))
return 0; // Error: return error from dec_char_sub()
// s1 = c3; // no write back, check only.
--i1;
}
while (s1 == '0' && yh < yt)// ignore beginning '0' in s1
++(yh);
return 1;
}
int sub_off_str(char * s1, int * h, int * t, char * s2, int ls2, int s)
{
int i1 = *t + s; // i1 is char index of s1
int i2 = ls2 - 1; // i2 is char index of s2
char borrow = '0'; // borrow is a borrow
char c1, c2, c3; // c1, c2 and c3 are temp chars
while (i2 >= 0) // loop from the tail char to the head char of s2
{
if (i1 < 0) // Error: not enough space in s1
return 0;
while (i1 < *h) // fill '0' before s1 if necessary
{
--(*h);
if (*h < 0) // Error: not enough space in s1
return 0;
s1[*h] = '0';
}
c1 = s1;
c2 = s2;
if (0 == dec_char_sub(borrow, c1, c2, &borrow, &c3))
return 0; // Error: return error from dec_char_sub()
s1 = c3;
--i1;
--i2;
}
while (borrow == '1')// continue with i1: loop until borrow =='0'
{
if (i1 < 0) // Error: not enough space in s1
return 0;
if (i1 < *h) // Error: s1 < s2
return -1;
c1 = s1;
c2 = '0';
if (0 == dec_char_sub(borrow, c1, c2, &borrow, &c3))
return 0; // Error: return error from dec_char_sub()
s1 = c3;
--i1;
}
while (s1[*h] == '0' && *h < *t)// ignore beginning '0' in s1
++(*h);
return 1;
}
int add_up_str(char * s1, int * h, int * t, char * s2, int ls2, int s)
{
int i1 = *t + s; // i1 is char index of s1
int i2 = ls2 - 1; // i2 is char index of s2
char carry = '0'; // carry is a carry
char c1, c2, c3; // c1, c2 and c3 are temp chars
while (i2 >= 0) // loop from the tail char to the head char of s2
{
if (i1 < 0) // Error: not enough space in s1
return 0;
while (i1 < *h) // fill '0' before s1 if necessary
{
--(*h);
if (*h < 0) // Error: not enough space in s1
return 0;
s1[*h] = '0';
}
c1 = s1;
c2 = s2;
if (0 == dec_char_add(carry, c1, c2, &carry, &c3))
return 0; // Error: return error from dec_char_add()
s1 = c3;
--i1;
--i2;
}
while (carry == '1') // continue with i1: loop until carry =='0'
{
if (i1 < 0) // Error: not enough space in s1
return 0;
while (i1 < *h) // fill '0' before s1 if necessary
{
--(*h);
if (*h < 0) // Error: not enough space in s1
return 0;
s1[*h] = '0';
}
c1 = s1;
c2 = '0';
if (0 == dec_char_add(carry, c1, c2, &carry, &c3))
return 0; // Error: return error from dec_char_add()
s1 = c3;
--i1;
}
return 1;
}
int dec_str_sub(char * str1, char * str2, char * str3, int str3_array_size, int * offset)
{
int pn1, pn2; //indicate positive or negative for str1 and str2.
int iq1, iq2; //store integral part quantity for str1 and str2.
int dq1, dq2; //store decimal part quantity for str1 and str2.
int dp1, dp2; //store '.' position for str1 and str2.
int rt1, rt2, rt3; //temp return value;
rt1 = is_dec_str(str1, &pn1, &iq1, &dq1, &dp1);
if (rt1 == 0)
return 0; //Error: str1 is not a number.
rt2 = is_dec_str(str2, &pn2, &iq2, &dq2, &dp2);
if (rt2 == 0)
return 0; //Error: str2 is not a number.
if (pn1 == 1 && pn2 == -1) //str1 is positive, str2 is negative
{
rt3 = add_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
}
else if (pn1 == 1 && pn2 == 1) //str1 is positive, str2 is positive
{
rt3 = sub_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
if (rt3 == -1)
{ //switch str1 and str2, try again.
rt3 = sub_ip_dp(str2, dp2, iq2, dq2, str1, dp1, iq1, dq1,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed again finally.
if (--(*offset) >= 0)
str3[*offset] = '-'; //put on a '-' for str3
else
return 0; //Error: not enough space in str3
}
}
else if (pn1 == -1 && pn2 == -1) //str1 is negative, str2 is negative
{
rt3 = sub_ip_dp(str2, dp2, iq2, dq2, str1, dp1, iq1, dq1,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
if (rt3 == -1)
{ //switch str1 and str2, try again.
rt3 = sub_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed again finally.
if (--(*offset) >= 0)
str3[*offset] = '-'; //put on a '-' for str3
else
return 0; //Error: not enough space in str3
}
}
else if (pn1 == -1 && pn2 == 1) //str1 is negative, str2 is positive
{
rt3 = add_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
if (str3[*offset] == '0' && str3[*offset+1] == '\0')
; //do nothing, it's 0, don't put on '-', happened while (-0) - (0)
else
{
if (--(*offset) >= 0)
str3[*offset] = '-'; //put on a '-' for str3
else
return 0; //Error: not enough space in str3
}
}
else
return 0; //Error: something wrong, not possible.
return 1; //Done.
}
int dec_str_add(char * str1, char * str2, char * str3, int str3_array_size, int * offset)
{
int pn1, pn2; //indicate positive or negative for str1 and str2.
int iq1, iq2; //store integral part quantity for str1 and str2.
int dq1, dq2; //store decimal part quantity for str1 and str2.
int dp1, dp2; //store '.' position for str1 and str2.
int rt1, rt2, rt3; //temp return value;
rt1 = is_dec_str(str1, &pn1, &iq1, &dq1, &dp1);
if (rt1 == 0)
return 0; //Error: str1 is not a number.
rt2 = is_dec_str(str2, &pn2, &iq2, &dq2, &dp2);
if (rt2 == 0)
return 0; //Error: str2 is not a number.
if (pn1 == 1 && pn2 == 1) //str1 is positive, str2 is positive
{
rt3 = add_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
}
else if (pn1 == 1 && pn2 == -1) //str1 is positive, str2 is negative
{
rt3 = sub_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
if (rt3 == -1)
{ //switch str1 and str2, try again.
rt3 = sub_ip_dp(str2, dp2, iq2, dq2, str1, dp1, iq1, dq1,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed again finally.
if (--(*offset) >= 0)
str3[*offset] = '-'; //put on a '-' for str3
else
return 0; //Error: not enough space in str3
}
}
else if (pn1 == -1 && pn2 == 1) //str1 is negative, str2 is positive
{
rt3 = sub_ip_dp(str2, dp2, iq2, dq2, str1, dp1, iq1, dq1,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
if (rt3 == -1)
{ //switch str1 and str2, try again.
rt3 = sub_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed again finally.
if (--(*offset) >= 0)
str3[*offset] = '-'; //put on a '-' for str3
else
return 0; //Error: not enough space in str3
}
}
else if (pn1 == -1 && pn2 == -1) //str1 is negative, str2 is negative
{
rt3 = add_ip_dp(str1, dp1, iq1, dq1, str2, dp2, iq2, dq2,
str3, str3_array_size, offset);
if (rt3 == 0)
return 0; //Error: failed, maybe, not enough space in str3
if (str3[*offset] == '0' && str3[*offset+1] == '\0')
; //do nothing, it's 0, don't put on '-', happened while (-0) + (-0)
else
{
if (--(*offset) >= 0)
str3[*offset] = '-'; //put on a '-' for str3
else
return 0; //Error: not enough space in str3
}
}
else
return 0; //Error: something wrong, not possible.
return 1; //Done.
}
int sub_ip_dp(char * str1, int dot_pos1, int i_qty1, int d_qty1,
char * str2, int dot_pos2, int i_qty2, int d_qty2,
char * str3, int str3_array_size, int * offset)
{
//return 1 if no error, -1 if sub error (str1 < str2), 0 if other errors.
char * p1 = str1 + dot_pos1; // p1 is a pointer to '.' or '\0' of str1
char * p2 = str2 + dot_pos2; // p2 is a pointer to '.' or '\0' of str2
int i = str3_array_size; // i is an index of str3, copy to *offset finally
char borrow = '0'; // borrow is a borrow
char c1, c2, c3; // c1, c2 and c3 are temp chars
int k, j; // k and j are temp index
// set '\0' at the end of str3
if (--i >= 0)
str3 = '\0';
else
return 0; //Error: insufficient space in str3
// sub decimal part: from tail to head
k = (d_qty1 > d_qty2) ? d_qty1 : d_qty2;
while (k > 0)
{
c1 = (k > d_qty1) ? '0' : p1;
c2 = (k > d_qty2) ? '0' : p2;
if (0 == dec_char_sub(borrow, c1, c2, &borrow, &c3))
return 0; //Error: return error from dec_char_add()
if (--i >= 0)
str3 = c3;
else
return 0; //Error: insufficient space in str3
if (str3 == '\0' && str3 == '0')
i++; //ignore '0' in the end of decimal
--k;
}
// put a '.' in the string
if (str3 != '\0')
{
if (--i >= 0)
str3 = '.';
else
return 0; //Error: insufficient space in str3
}
// sub integral part: from tail to head
k = 1;
j = (i_qty1 > i_qty2) ? i_qty1 : i_qty2;
while (k <= j)
{
c1 = (k > i_qty1) ? '0' : p1[-k];
c2 = (k > i_qty2) ? '0' : p2[-k];
if (0 == dec_char_sub(borrow, c1, c2, &borrow, &c3))
return 0; //Error: return error from dec_char_add()
if (--i >= 0)
str3 = c3;
else
return 0; //Error: insufficient space in str3
++k;
}
// consider borrow after last dec_char_sub()
if (borrow == '1')
return -1; //Error: str1 is smaller than str2, it's not allowed
//you should switch str1 and str2
//try again: - (str2 - str1)
// ignore all begining '0' in the string
while (str3 == '0')
++i;
// add a '0' if start with a '.'
if (str3 == '.')
{
if (--i >= 0)
str3 = '0';
else
return 0; //Error: insufficient space in str3
}
// add a '0' if empty string
if (str3 == '\0')
{
if (--i >= 0)
str3 = '0';
else
return 0; //Error: insufficient space in str3
}
// set *offset for str3
*offset = i;
return 1; //Done
}
int add_ip_dp(char * str1, int dot_pos1, int i_qty1, int d_qty1,
char * str2, int dot_pos2, int i_qty2, int d_qty2,
char * str3, int str3_array_size, int * offset)
{
//return 1 = no error, 0 = fail.
char * p1 = str1 + dot_pos1; // p1 is a pointer to '.' or '\0' of str1
char * p2 = str2 + dot_pos2; // p2 is a pointer to '.' or '\0' of str2
int i = str3_array_size; // i is an index of str3, copy to *offset finally
char carry = '0'; // carry is a carry
char c1, c2, c3; // c1, c2 and c3 are temp chars
int k, j; // k and j are temp index
// set '\0' at the end of str3
if (--i >= 0)
str3 = '\0';
else
return 0; //Error: insufficient space in str3
// add decimal part: from tail to head
k = (d_qty1 > d_qty2) ? d_qty1 : d_qty2;
while (k > 0)
{
c1 = (k > d_qty1) ? '0' : p1;
c2 = (k > d_qty2) ? '0' : p2;
if (0 == dec_char_add(carry, c1, c2, &carry, &c3))
return 0; //Error: return error from dec_char_add()
if (--i >= 0)
str3 = c3;
else
return 0; //Error: insufficient space in str3
if (str3 == '\0' && str3 == '0')
i++; //ignore '0' in the end of decimal
--k;
}
// put a '.' in the string
if (str3 != '\0')
{
if (--i >= 0)
str3 = '.';
else
return 0; //Error: insufficient space in str3
}
// add integral part: from tail to head
k = 1;
j = (i_qty1 > i_qty2) ? i_qty1 : i_qty2;
while (k <= j)
{
c1 = (k > i_qty1) ? '0' : p1[-k];
c2 = (k > i_qty2) ? '0' : p2[-k];
if (0 == dec_char_add(carry, c1, c2, &carry, &c3))
return 0; //Error: return error from dec_char_add()
if (--i >= 0)
str3 = c3;
else
return 0; //Error: insufficient space in str3
++k;
}
// consider carry after last dec_char_add()
if (carry == '1')
{
if (--i >= 0)
str3 = '1';
else
return 0; //Error: insufficient space in str3
}
// ignore all begining '0' in the string
while (str3 == '0')
++i;
// add a '0' if start with a '.'
if (str3 == '.')
{
if (--i >= 0)
str3 = '0';
else
return 0; //Error: insufficient space in str3
}
// add a '0' if empty string
if (str3 == '\0')
{
if (--i >= 0)
str3 = '0';
else
return 0; //Error: insufficient space in str3
}
// set *offset for str3
*offset = i;
return 1; //Done
}
int is_dec_str(char * str, int * p_or_n, int * i_qty, int * d_qty, int * dot_pos)
{
int ret_val = 1; //return value, 1 = Yes, 0 = No.
int dot_qty = 0; //'.' qty found in the str
int i = 0; //i is an index of str.
switch (str)
{
case '-': *p_or_n = -1; i++; break; //negative number and bypass the '-'
case '+': i++; //bypass the '+'
default: *p_or_n = 1; //positive number
}
*i_qty = 0;
*d_qty = 0;
*dot_pos = -1; //initialized as a not possible value.
while (ret_val == 1 && str != '\0')
{
switch (str)
{
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9': dot_qty ? ++(*d_qty) : ++(*i_qty);
break;
case '.': if (++dot_qty > 1)
ret_val = 0; //Error: too many '.'
*dot_pos = i;
break;
default: ret_val = 0; //Error: unexpected char found
}
i++;
}
if (*i_qty == 0 && *d_qty == 0)
ret_val = 0; //Error: no valid number found
if (ret_val == 1)
{
if (*dot_pos == -1) //there is no '.' in the str, str is an integer
*dot_pos = i; //dot_pos set at '\0'(str end) for "no dot" integer
if (*i_qty > 0)
while (*d_qty > 0 && str[*dot_pos + *d_qty] == '0')
--(*d_qty); //ignore excessive '0' in the end of decimal part
else
while (*d_qty > 1 && str[*dot_pos + *d_qty] == '0')
--(*d_qty); //ignore excessive '0' in the end of decimal part(leave 1)
if (*d_qty > 0)
while (*i_qty > 0 && str[*dot_pos - *i_qty] == '0')
--(*i_qty); //ignore excessive '0' in the begining of integeral part
else
while (*i_qty > 1 && str[*dot_pos - *i_qty] == '0')
--(*i_qty); //ignore excessive '0' in the begining of integeral part(leave 1)
}
else
{
*p_or_n = 0;
*i_qty = 0;
*d_qty = 0;
*dot_pos = 0;
}
return ret_val;
}
int dec_char_sub(char in_borrow, char c1, char c2, char * out_borrow, char * result)
{
int ret_val = 1; //return value, 1 = no error, otherwise 0
switch (c1) //go through "switch case" to get answer without calculate.
{
case '0': switch (c2)
{
case '0': *out_borrow = '0'; *result = '0'; break;
case '1': *out_borrow = '1'; *result = '9'; break;
case '2': *out_borrow = '1'; *result = '8'; break;
case '3': *out_borrow = '1'; *result = '7'; break;
case '4': *out_borrow = '1'; *result = '6'; break;
case '5': *out_borrow = '1'; *result = '5'; break;
case '6': *out_borrow = '1'; *result = '4'; break;
case '7': *out_borrow = '1'; *result = '3'; break;
case '8': *out_borrow = '1'; *result = '2'; break;
case '9': *out_borrow = '1'; *result = '1'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '1': switch (c2)
{
case '0': *out_borrow = '0'; *result = '1'; break;
case '1': *out_borrow = '0'; *result = '0'; break;
case '2': *out_borrow = '1'; *result = '9'; break;
case '3': *out_borrow = '1'; *result = '8'; break;
case '4': *out_borrow = '1'; *result = '7'; break;
case '5': *out_borrow = '1'; *result = '6'; break;
case '6': *out_borrow = '1'; *result = '5'; break;
case '7': *out_borrow = '1'; *result = '4'; break;
case '8': *out_borrow = '1'; *result = '3'; break;
case '9': *out_borrow = '1'; *result = '2'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '2': switch (c2)
{
case '0': *out_borrow = '0'; *result = '2'; break;
case '1': *out_borrow = '0'; *result = '1'; break;
case '2': *out_borrow = '0'; *result = '0'; break;
case '3': *out_borrow = '1'; *result = '9'; break;
case '4': *out_borrow = '1'; *result = '8'; break;
case '5': *out_borrow = '1'; *result = '7'; break;
case '6': *out_borrow = '1'; *result = '6'; break;
case '7': *out_borrow = '1'; *result = '5'; break;
case '8': *out_borrow = '1'; *result = '4'; break;
case '9': *out_borrow = '1'; *result = '3'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '3': switch (c2)
{
case '0': *out_borrow = '0'; *result = '3'; break;
case '1': *out_borrow = '0'; *result = '2'; break;
case '2': *out_borrow = '0'; *result = '1'; break;
case '3': *out_borrow = '0'; *result = '0'; break;
case '4': *out_borrow = '1'; *result = '9'; break;
case '5': *out_borrow = '1'; *result = '8'; break;
case '6': *out_borrow = '1'; *result = '7'; break;
case '7': *out_borrow = '1'; *result = '6'; break;
case '8': *out_borrow = '1'; *result = '5'; break;
case '9': *out_borrow = '1'; *result = '4'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '4': switch (c2)
{
case '0': *out_borrow = '0'; *result = '4'; break;
case '1': *out_borrow = '0'; *result = '3'; break;
case '2': *out_borrow = '0'; *result = '2'; break;
case '3': *out_borrow = '0'; *result = '1'; break;
case '4': *out_borrow = '0'; *result = '0'; break;
case '5': *out_borrow = '1'; *result = '9'; break;
case '6': *out_borrow = '1'; *result = '8'; break;
case '7': *out_borrow = '1'; *result = '7'; break;
case '8': *out_borrow = '1'; *result = '6'; break;
case '9': *out_borrow = '1'; *result = '5'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '5': switch (c2)
{
case '0': *out_borrow = '0'; *result = '5'; break;
case '1': *out_borrow = '0'; *result = '4'; break;
case '2': *out_borrow = '0'; *result = '3'; break;
case '3': *out_borrow = '0'; *result = '2'; break;
case '4': *out_borrow = '0'; *result = '1'; break;
case '5': *out_borrow = '0'; *result = '0'; break;
case '6': *out_borrow = '1'; *result = '9'; break;
case '7': *out_borrow = '1'; *result = '8'; break;
case '8': *out_borrow = '1'; *result = '7'; break;
case '9': *out_borrow = '1'; *result = '6'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '6': switch (c2)
{
case '0': *out_borrow = '0'; *result = '6'; break;
case '1': *out_borrow = '0'; *result = '5'; break;
case '2': *out_borrow = '0'; *result = '4'; break;
case '3': *out_borrow = '0'; *result = '3'; break;
case '4': *out_borrow = '0'; *result = '2'; break;
case '5': *out_borrow = '0'; *result = '1'; break;
case '6': *out_borrow = '0'; *result = '0'; break;
case '7': *out_borrow = '1'; *result = '9'; break;
case '8': *out_borrow = '1'; *result = '8'; break;
case '9': *out_borrow = '1'; *result = '7'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '7': switch (c2)
{
case '0': *out_borrow = '0'; *result = '7'; break;
case '1': *out_borrow = '0'; *result = '6'; break;
case '2': *out_borrow = '0'; *result = '5'; break;
case '3': *out_borrow = '0'; *result = '4'; break;
case '4': *out_borrow = '0'; *result = '3'; break;
case '5': *out_borrow = '0'; *result = '2'; break;
case '6': *out_borrow = '0'; *result = '1'; break;
case '7': *out_borrow = '0'; *result = '0'; break;
case '8': *out_borrow = '1'; *result = '9'; break;
case '9': *out_borrow = '1'; *result = '8'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '8': switch (c2)
{
case '0': *out_borrow = '0'; *result = '8'; break;
case '1': *out_borrow = '0'; *result = '7'; break;
case '2': *out_borrow = '0'; *result = '6'; break;
case '3': *out_borrow = '0'; *result = '5'; break;
case '4': *out_borrow = '0'; *result = '4'; break;
case '5': *out_borrow = '0'; *result = '3'; break;
case '6': *out_borrow = '0'; *result = '2'; break;
case '7': *out_borrow = '0'; *result = '1'; break;
case '8': *out_borrow = '0'; *result = '0'; break;
case '9': *out_borrow = '1'; *result = '9'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '9': switch (c2)
{
case '0': *out_borrow = '0'; *result = '9'; break;
case '1': *out_borrow = '0'; *result = '8'; break;
case '2': *out_borrow = '0'; *result = '7'; break;
case '3': *out_borrow = '0'; *result = '6'; break;
case '4': *out_borrow = '0'; *result = '5'; break;
case '5': *out_borrow = '0'; *result = '4'; break;
case '6': *out_borrow = '0'; *result = '3'; break;
case '7': *out_borrow = '0'; *result = '2'; break;
case '8': *out_borrow = '0'; *result = '1'; break;
case '9': *out_borrow = '0'; *result = '0'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
default: ret_val = 1; //Error: c1 out of range
}
switch (in_borrow) //go through "switch case" to get answer without calculate.
{
case '0': break;
case '1': switch (*result)
{
case '0': *out_borrow = '1'; *result = '9'; break;
case '1': *result = '0'; break;
case '2': *result = '1'; break;
case '3': *result = '2'; break;
case '4': *result = '3'; break;
case '5': *result = '4'; break;
case '6': *result = '5'; break;
case '7': *result = '6'; break;
case '8': *result = '7'; break;
case '9': *result = '8'; break;
}
break;
default: ret_val = 0; //Error: in_carry out of range
}
if (ret_val != 1)
{
*out_borrow = '0';
*result = '0';
}
return ret_val;
}
int dec_char_add(char in_carry, char c1, char c2, char * out_carry, char * result)
{
int ret_val = 1; //return value, 1 = no error, otherwise 0
switch (c1) //go through "switch case" to get answer without calculate.
{
case '0': switch (c2)
{
case '0': *out_carry = '0'; *result = '0'; break;
case '1': *out_carry = '0'; *result = '1'; break;
case '2': *out_carry = '0'; *result = '2'; break;
case '3': *out_carry = '0'; *result = '3'; break;
case '4': *out_carry = '0'; *result = '4'; break;
case '5': *out_carry = '0'; *result = '5'; break;
case '6': *out_carry = '0'; *result = '6'; break;
case '7': *out_carry = '0'; *result = '7'; break;
case '8': *out_carry = '0'; *result = '8'; break;
case '9': *out_carry = '0'; *result = '9'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '1': switch (c2)
{
case '0': *out_carry = '0'; *result = '1'; break;
case '1': *out_carry = '0'; *result = '2'; break;
case '2': *out_carry = '0'; *result = '3'; break;
case '3': *out_carry = '0'; *result = '4'; break;
case '4': *out_carry = '0'; *result = '5'; break;
case '5': *out_carry = '0'; *result = '6'; break;
case '6': *out_carry = '0'; *result = '7'; break;
case '7': *out_carry = '0'; *result = '8'; break;
case '8': *out_carry = '0'; *result = '9'; break;
case '9': *out_carry = '1'; *result = '0'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '2': switch (c2)
{
case '0': *out_carry = '0'; *result = '2'; break;
case '1': *out_carry = '0'; *result = '3'; break;
case '2': *out_carry = '0'; *result = '4'; break;
case '3': *out_carry = '0'; *result = '5'; break;
case '4': *out_carry = '0'; *result = '6'; break;
case '5': *out_carry = '0'; *result = '7'; break;
case '6': *out_carry = '0'; *result = '8'; break;
case '7': *out_carry = '0'; *result = '9'; break;
case '8': *out_carry = '1'; *result = '0'; break;
case '9': *out_carry = '1'; *result = '1'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '3': switch (c2)
{
case '0': *out_carry = '0'; *result = '3'; break;
case '1': *out_carry = '0'; *result = '4'; break;
case '2': *out_carry = '0'; *result = '5'; break;
case '3': *out_carry = '0'; *result = '6'; break;
case '4': *out_carry = '0'; *result = '7'; break;
case '5': *out_carry = '0'; *result = '8'; break;
case '6': *out_carry = '0'; *result = '9'; break;
case '7': *out_carry = '1'; *result = '0'; break;
case '8': *out_carry = '1'; *result = '1'; break;
case '9': *out_carry = '1'; *result = '2'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '4': switch (c2)
{
case '0': *out_carry = '0'; *result = '4'; break;
case '1': *out_carry = '0'; *result = '5'; break;
case '2': *out_carry = '0'; *result = '6'; break;
case '3': *out_carry = '0'; *result = '7'; break;
case '4': *out_carry = '0'; *result = '8'; break;
case '5': *out_carry = '0'; *result = '9'; break;
case '6': *out_carry = '1'; *result = '0'; break;
case '7': *out_carry = '1'; *result = '1'; break;
case '8': *out_carry = '1'; *result = '2'; break;
case '9': *out_carry = '1'; *result = '3'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '5': switch (c2)
{
case '0': *out_carry = '0'; *result = '5'; break;
case '1': *out_carry = '0'; *result = '6'; break;
case '2': *out_carry = '0'; *result = '7'; break;
case '3': *out_carry = '0'; *result = '8'; break;
case '4': *out_carry = '0'; *result = '9'; break;
case '5': *out_carry = '1'; *result = '0'; break;
case '6': *out_carry = '1'; *result = '1'; break;
case '7': *out_carry = '1'; *result = '2'; break;
case '8': *out_carry = '1'; *result = '3'; break;
case '9': *out_carry = '1'; *result = '4'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '6': switch (c2)
{
case '0': *out_carry = '0'; *result = '6'; break;
case '1': *out_carry = '0'; *result = '7'; break;
case '2': *out_carry = '0'; *result = '8'; break;
case '3': *out_carry = '0'; *result = '9'; break;
case '4': *out_carry = '1'; *result = '0'; break;
case '5': *out_carry = '1'; *result = '1'; break;
case '6': *out_carry = '1'; *result = '2'; break;
case '7': *out_carry = '1'; *result = '3'; break;
case '8': *out_carry = '1'; *result = '4'; break;
case '9': *out_carry = '1'; *result = '5'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '7': switch (c2)
{
case '0': *out_carry = '0'; *result = '7'; break;
case '1': *out_carry = '0'; *result = '8'; break;
case '2': *out_carry = '0'; *result = '9'; break;
case '3': *out_carry = '1'; *result = '0'; break;
case '4': *out_carry = '1'; *result = '1'; break;
case '5': *out_carry = '1'; *result = '2'; break;
case '6': *out_carry = '1'; *result = '3'; break;
case '7': *out_carry = '1'; *result = '4'; break;
case '8': *out_carry = '1'; *result = '5'; break;
case '9': *out_carry = '1'; *result = '6'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '8': switch (c2)
{
case '0': *out_carry = '0'; *result = '8'; break;
case '1': *out_carry = '0'; *result = '9'; break;
case '2': *out_carry = '1'; *result = '0'; break;
case '3': *out_carry = '1'; *result = '1'; break;
case '4': *out_carry = '1'; *result = '2'; break;
case '5': *out_carry = '1'; *result = '3'; break;
case '6': *out_carry = '1'; *result = '4'; break;
case '7': *out_carry = '1'; *result = '5'; break;
case '8': *out_carry = '1'; *result = '6'; break;
case '9': *out_carry = '1'; *result = '7'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
case '9': switch (c2)
{
case '0': *out_carry = '0'; *result = '9'; break;
case '1': *out_carry = '1'; *result = '0'; break;
case '2': *out_carry = '1'; *result = '1'; break;
case '3': *out_carry = '1'; *result = '2'; break;
case '4': *out_carry = '1'; *result = '3'; break;
case '5': *out_carry = '1'; *result = '4'; break;
case '6': *out_carry = '1'; *result = '5'; break;
case '7': *out_carry = '1'; *result = '6'; break;
case '8': *out_carry = '1'; *result = '7'; break;
case '9': *out_carry = '1'; *result = '8'; break;
default: ret_val = 0; //Error: c2 out of range
}
break;
default: ret_val = 0; //Error: c1 out of range
}
switch (in_carry) //go through "switch case" to get answer without calculate.
{
case '0': break;
case '1': switch (*result)
{
case '0': *result = '1'; break;
case '1': *result = '2'; break;
case '2': *result = '3'; break;
case '3': *result = '4'; break;
case '4': *result = '5'; break;
case '5': *result = '6'; break;
case '6': *result = '7'; break;
case '7': *result = '8'; break;
case '8': *result = '9'; break;
case '9': *out_carry = '1'; *result = '0'; break;
}
break;
default: ret_val = 0; //Error: in_carry out of range
}
if (ret_val != 1)
{
*out_carry = '0';
*result = '0';
}
return ret_val;
}
厉害啊,虽然不知道有什么用 之前做过类似的，是模拟小学的时候手算加减乘除的过程，还实现了幂和阶乘的计算。 万神fake 发表于 2024-10-8 10:39
厉害啊,虽然不知道有什么用
这个可以计算：
99999999999999999999999999999999 + 0.00000000000000000000000000000001 ~零度 发表于 2024-10-8 13:01
之前做过类似的，是模拟小学的时候手算加减乘除的过程，还实现了幂和阶乘的计算。
这个加减乘除和列竖式手工计算是一样的。没有高科技，硬来的。 我记得le有个题，是字符数字计算，就有大数问题
楼主是个勤劳的码农
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