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#include <string.h>
#include <stdio.h>
#include <stdlib.h>
void encode(char *src, int src_len, char *dst)
{
int i = 0, j = 0;
char base64_map[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (; i < src_len - src_len % 3; i += 3) {
dst[j++] = base64_map[(src[i] >> 2) & 0x3F];
dst[j++] = base64_map[((src[i] << 4) & 0x30) + ((src[i + 1] >> 4) & 0xF)];
dst[j++] = base64_map[((src[i + 1] << 2) & 0x3C) + ((src[i + 2] >> 6) & 0x3)];
dst[j++] = base64_map[src[i + 2] & 0x3F];
}
if (src_len % 3 == 1) {
dst[j++] = base64_map[(src[i] >> 2) & 0x3F];
dst[j++] = base64_map[(src[i] << 4) & 0x30];
dst[j++] = '=';
dst[j++] = '=';
}
else if (src_len % 3 == 2) {
dst[j++] = base64_map[(src[i] >> 2) & 0x3F];
dst[j++] = base64_map[((src[i] << 4) & 0x30) + ((src[i + 1] >> 4) & 0xF)];
dst[j++] = base64_map[(src[i + 1] << 2) & 0x3C];
dst[j++] = '=';
}
dst[j] = '\0';
}
void decode(char *src, int src_len, char *dst)
{
int i = 0, j = 0;
char base64_decode_map[256] = {
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255,
255, 0, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 26, 27, 28,
29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255};
for (; i < src_len; i += 4) {
dst[j++] = base64_decode_map[src[i]] << 2 |
base64_decode_map[src[i + 1]] >> 4;
dst[j++] = base64_decode_map[src[i + 1]] << 4 |
base64_decode_map[src[i + 2]] >> 2;
dst[j++] = base64_decode_map[src[i + 2]] << 6 |
base64_decode_map[src[i + 3]];
}
dst[j] = '\0';
}
int main( int argc, char* argv[])
{
int i,size;
unsigned char input[1024] = {'\0'};
unsigned char output[1024] = {'\0'};
if (argc <= 2)
{
printf("Usage: string encode and decode.\n");
printf("\t\tbase64 -e decode string\t\tencode string.\n");
printf("\t\tbase64 -d encode string\t\tdecode string.\n");
exit(1);
}
size = strlen(argv[2]);
strncpy(input, argv[2], size);
printf("需要进行处理的数据: <%s>\n", input);
if (!strncmp(argv[1], "-e", 2))
{
encode(input, size, output);
printf("base64编码后的数据: <%s>\n", output);
}
else if (!strncmp(argv[1], "-d", 2))
{
decode(input, size, output);
printf("base64解码后的数据: <%s>\n", output);
}
return 0;
}
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