【分享】C语言实现base64编解码图片

cui_boran

代码：

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

const char * base64char = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

char * base64_encode( const unsigned char * bindata, char * base64, int binlength )
{
    int i, j;
    unsigned char current;

    for ( i = 0, j = 0 ; i < binlength ; i += 3 )
    {
        current = (bindata[i] >> 2) ;
        current &= (unsigned char)0x3F;
        base64[j++] = base64char[(int)current];

        current = ( (unsigned char)(bindata[i] << 4 ) ) & ( (unsigned char)0x30 ) ;
        if ( i + 1 >= binlength )
        {
            base64[j++] = base64char[(int)current];
            base64[j++] = '=';
            base64[j++] = '=';
            break;
        }
        current |= ( (unsigned char)(bindata[i+1] >> 4) ) & ( (unsigned char) 0x0F );
        base64[j++] = base64char[(int)current];

        current = ( (unsigned char)(bindata[i+1] << 2) ) & ( (unsigned char)0x3C ) ;
        if ( i + 2 >= binlength )
        {
            base64[j++] = base64char[(int)current];
            base64[j++] = '=';
            break;
        }
        current |= ( (unsigned char)(bindata[i+2] >> 6) ) & ( (unsigned char) 0x03 );
        base64[j++] = base64char[(int)current];

        current = ( (unsigned char)bindata[i+2] ) & ( (unsigned char)0x3F ) ;
        base64[j++] = base64char[(int)current];
    }
    base64[j] = '\0';
    return base64;
}

int base64_decode( const char * base64, unsigned char * bindata )
{
    int i, j;
    unsigned char k;
    unsigned char temp[4];
    for ( i = 0, j = 0; base64[i] != '\0' ; i += 4 )
    {
        memset( temp, 0xFF, sizeof(temp) );
        for ( k = 0 ; k < 64 ; k ++ )
        {
            if ( base64char[k] == base64[i] )
                temp[0]= k;
        }
        for ( k = 0 ; k < 64 ; k ++ )
        {
            if ( base64char[k] == base64[i+1] )
                temp[1]= k;
        }
        for ( k = 0 ; k < 64 ; k ++ )
        {
            if ( base64char[k] == base64[i+2] )
                temp[2]= k;
        }
        for ( k = 0 ; k < 64 ; k ++ )
        {
            if ( base64char[k] == base64[i+3] )
                temp[3]= k;
        }

        bindata[j++] = ((unsigned char)(((unsigned char)(temp[0] << 2))&0xFC)) |
                ((unsigned char)((unsigned char)(temp[1]>>4)&0x03));
        if ( base64[i+2] == '=' )
            break;

        bindata[j++] = ((unsigned char)(((unsigned char)(temp[1] << 4))&0xF0)) |
                ((unsigned char)((unsigned char)(temp[2]>>2)&0x0F));
        if ( base64[i+3] == '=' )
            break;

        bindata[j++] = ((unsigned char)(((unsigned char)(temp[2] << 6))&0xF0)) |
                ((unsigned char)(temp[3]&0x3F));
    }
    return j;
}

int main()
{        

        //打开图片
        FILE *fp = NULL;
        unsigned int size;         //图片字节数
        char *buffer;
        char *buffer1;
        size_t result;
        char *ret1; 
        unsigned int length;

        fp = fopen("tc2.jpg","rb");
        if (NULL == fp)
    {
            printf("open_error");
                exit(1);
    }

        //获取图片大小
        fseek(fp, 0L, SEEK_END);
        size = ftell(fp);
        fseek(fp, 0L, SEEK_SET);

        //分配内存存储整个图片
        buffer = (char *)malloc((size/4+1)*4);
        if (NULL == buffer)
    {
            printf("memory_error");
            exit(2);
    }

        //将图片拷贝到buffer
        result = fread(buffer, 1, size, fp);
         if (result != size)  
    {  
        printf("reading_error");  
        exit (3);  
    }  
    fclose(fp);

        //base64编码
        buffer1 = (char *)malloc((size/4+1)*4);
        if (NULL == buffer1)
    {
            printf("memory_error");
            exit(2);
    }
    ret1 = base64_encode(buffer, buffer1, size);
    length = strlen(buffer1);
    printf("%s\n", buffer1);

        free(buffer);
        free(buffer1);
        return 0;
}

注：  将程序中的tc2.jpg换成你需要编码的图片的路径就可以用了，也提供了解码函数可以调用。
最近在做图片上传，觉得这段base64编解码的代码很有用，分享给大家！
原帖地址：C语言对图片进行base64编码

wddtt

谢谢楼主啊

6f7a8d

厉害，学习了

yhgfwly007

感谢分享，厉害了，楼主