本文代码为从PHP代码中修改而来，只保留了2个函数。

int php_url_decode(char *str, int len);

char *php_url_encode(char const *s, int len, int *new_length);

URL编码做了如下操作：

字符"a"-"z"，"A"-"Z"，"0"-"9"，"."，"-"，"*"，和"_" 都不被编码，维持原值；

空格" "被转换为加号"+"。

其他每个字节都被表示成"%xy"格式的由3个字符组成的字符串，编码为UTF-8。

#include

#include

#include

#include

#include

static unsigned char hexchars[] = "0123456789ABCDEF";

static int php_htoi(char *s)

{

int value;

int c;

c = ((unsigned char *)s)[0];

if (isupper(c))

c = tolower(c);

value = (c >= ‘0‘ && c <= ‘9‘ ? c - ‘0‘ : c - ‘a‘ + 10) * 16;

c = ((unsigned char *)s)[1];

if (isupper(c))

c = tolower(c);

value += c >= ‘0‘ && c <= ‘9‘ ? c - ‘0‘ : c - ‘a‘ + 10;

return (value);

}

char *php_url_encode(char const *s, int len, int *new_length)

{

register unsigned char c;

unsigned char *to, *start;

unsigned char const *from, *end;

from = (unsigned char *)s;

end = (unsigned char *)s + len;

start = to = (unsigned char *) calloc(1, 3*len+1);

while (from < end)

{

c = *from++;

if (c == ‘ ‘)

{

*to++ = ‘+‘;

}

else if ((c < ‘0‘ && c != ‘-‘ && c != ‘.‘) ||

(c < ‘A‘ && c > ‘9‘) ||

(c > ‘Z‘ && c < ‘a‘ && c != ‘_‘) ||

(c > ‘z‘))

{

to[0] = ‘%‘;

to[1] = hexchars[c >> 4];

to[2] = hexchars[c & 15];

to += 3;

}

else

{

*to++ = c;

}

}

*to = 0;

if (new_length)

{

*new_length = to - start;

}

return (char *) start;

}

int php_url_decode(char *str, int len)

{

char *dest = str;

char *data = str;

while (len--)

{

if (*data == ‘+‘)

{

*dest = ‘ ‘;

}

else if (*data == ‘%‘ && len >= 2 && isxdigit((int) *(data + 1)) && isxdigit((int) *(data + 2)))

{

*dest = (char) php_htoi(data + 1);

data += 2;

len -= 2;

}

else

{

*dest = *data;

}

data++;

dest++;

}

*dest = ‘\0‘;

return dest - str;

}

int main(int argc, char ** argv)

{

char *str = "你好，世界！",*new_str;

int len = 0,new_len = 0,old_len = 0;

len = strlen(str);

new_str = php_url_encode(str,len,&new_len);

printf("new string : %s,new length : %d\n",new_str,new_len);

old_len = php_url_decode(new_str,new_len);

printf("old string : %s,old length : %d\n",new_str,old_len);

return 0;

}

ps：查了好多资料才弄明白urldecode的原理，原来如此简单，呵呵

时间： 09-06