C/C++ URL编码，解码（提取自PHP）

偶然发现，网上已经有很多对PHP的URL编解码函数提取的文章，但我还是想自己提取一次。看到网上那些文章，居然还保留着无用的代码片段，例如：os_toassii 那一段。
URL解码函数：

/* {{{ php_htoi
*/
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);
}
/* }}} */

/* {{{ URL解码，提取自PHP 5.2.17
用法：string urldecode(string str_source)
时间：2012-8-14 By Dewei
*/
string urldecode(string &str_source)
{
char const *in_str = str_source.c_str();
int in_str_len = strlen(in_str);
int out_str_len = 0;
string out_str;
char *str;

str = _strdup(in_str);
char *dest = str;
char *data = str;

while (in_str_len--) {
if (*data == '+') {
*dest = ' ';
}
else if (*data == '%' && in_str_len >= 2 && isxdigit((int) *(data + 1))
&& isxdigit((int) *(data + 2))) {
*dest = (char) php_htoi(data + 1);
data += 2;
in_str_len -= 2;
} else {
*dest = *data;
}
data++;
dest++;
}
*dest = '\0';
out_str_len = dest - str;
out_str = str;
free(str);
return out_str;
}
/* }}} */

URL编码函数：
/* {{{ URL编码，提取自PHP
用法：string urlencode(string str_source)
说明：仅不编码 -_. 其余全部编码，空格会被编码为 +
时间：2012-8-13 By Dewei
*/
string urlencode(string &str_source)
{
char const *in_str = str_source.c_str();
int in_str_len = strlen(in_str);
int out_str_len = 0;
string out_str;
register unsigned char c;
unsigned char *to, *start;
unsigned char const *from, *end;
unsigned char hexchars[] = "0123456789ABCDEF";

from = (unsigned char *)in_str;
end = (unsigned char *)in_str + in_str_len;
start = to = (unsigned char *) malloc(3*in_str_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;

out_str_len = to - start;
out_str = (char *) start;
free(start);
return out_str;
}
/* }}} */

/* {{{ URL编码CString版，提取自PHP 5.2.17
用法：CString urlencode(CString str_source)
说明：仅不编码 -_. 其余全部编码，空格会被编码为 +
时间：2012-8-13 By Dewei
*/
CString urlencode(CString &str_source)
{
char const *in_str = str_source;
int in_str_len = strlen(in_str);
int out_str_len = 0;
CString out_str = '\0';
register unsigned char c;
unsigned char *to, *start;
unsigned char const *from, *end;
unsigned char hexchars[] = "0123456789ABCDEF";

from = (unsigned char *)in_str;
end = (unsigned char *)in_str + in_str_len;
start = to = (unsigned char *) malloc(3*in_str_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;

out_str_len = to - start;
out_str = (char *) start;
free(start);
return out_str;
}

[本文转自：http://dewei.iteye.com/blog/1630969].