Mystrcat和StrReverse同时测试就会显示a越界

djdgf4

[C] 纯文本查看 复制代码

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string.h>
#include<math.h>


/*
*    1.实现字符串连结.例如"abc","xyz"->"abcxyz"
*      void Mystrcat(char *des,const char *src);//des+=src;
*    2.实现字符串比较.例如"abc","x"->小于0的数字;"abc","abbb"->大于0的数字;"abc","abc"->0
*       int Mystrcmp(const char *str1,const char *str2);
*    3.实现字符串转数字.例如"12345"->12345;"12a345"->12(遇到非数字字符转换结束);"ab12"->0
*       int Myatoi(const char *str);
*    4.实现字符串反转.例如"abc"->"cba";"abcd"->"dcba"
*       void StrReverse(char *str); 
*/

void Mystrcat(char* des, const char* src)
{
	int des_count  = 0 , src_count = 0 , i = 0 , j = 0;
	while (*(des + i )!= '\0')
	{
		des_count++;
		i++;
	}
	while (*(src + j ) != '\0')
	{
		src_count++;
		j++;
	}
	for (i = 0 ; i <= src_count; i++)
	{
		*(des + i + des_count) = *(src + i );
	}
}

int Mystrcmp(const char* str1, const char* str2)
{
	for (int i = 0; ; i++)
	{
		if (*str2 != '\0' && *str1 != '\0'
			)
		{
			if (*str1 > *str2)	return 1;//左边大返回正数
			else if (*str1 < *str2)	return -1;//右边大返回负数
		}
		else if (*str1 != '\0' && *str2 == '\0')		return 1;
		else if (*str1 == '\0' && *str2 != '\0')		return -1;
		else
		{
			return 0;
		}
	}
}

int Myatoi(const char* str)
{
	int flag = 0 , i =0;
	while(*(str + i ) != '\0')
	{
		if (*(str + i) < '9' && *(str + i) > '0') {
			flag = 10 * flag + *(str + i) - '0';
		}
		else break;
		i++;
	}
	return flag;
}

void StrReverse(char* str)
{
	int count = strlen(str) - 1;
	int start = 0;
	char tmp;

	while (start < count)
	{
		tmp = *(str + start);
		*(str + start) = *(str + count);
		*(str + count) = tmp;

		start++;
		count--;
	}
	
}

int main()
{
	char a[] = { "asd24dfs" };
	char b[] = { "354asdg" };
	char c[] = { "123456" };
	char d[] = { "sassdg" };
	Mystrcat(a, b); 
	printf("%s\n", a);
	Mystrcat(d, c);
	printf("%s\n", d);

	/*printf("%d\n",Mystrcmp(a, c));
	printf("%d\n", Mystrcmp(c, d));
	printf("%d\n", Mystrcmp(a, d));
	printf("%d\n", Mystrcmp(b, c));*/

	/*printf("%d\n", Myatoi(a));
	printf("%d\n", Myatoi(b));
	printf("%d\n", Myatoi(c));
	printf("%d\n", Myatoi(d));*/

	StrReverse(a);
	printf("%s\n", a);
	StrReverse(c);
	printf("%s\n", c);
}

only998

C风格字符串依赖 0 作为结束符，strlen也是检测的 \0 ，Mystrcat有添加 \0 ？