URL Encoding/Decoding in C
转自http://www.geekhideout.com/urlcode.shtml
最近我需要对url编码的字符串进行编码和解码。在对可用的代码进行了简短的搜索之后，我发现我看到的大多数代码都不是非常高效，或者编写得相当糟糕。我决定建立自己的日常生活，并在这里分享它们。
/* Converts a hex character to its integer value */
char from_hex(char ch) {
return isdigit(ch) ? ch - '0' : tolower(ch) - 'a' + 10;
}
/* Converts an integer value to its hex character*/
char to_hex(char code) {
static char hex[] = "0123456789abcdef";
return hex[code & 15];
}
/* Returns a url-encoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
char *url_encode(char *str) {
char *pstr = str, *buf = malloc(strlen(str) * 3 + 1), *pbuf = buf;
while (*pstr) {
if (isalnum(*pstr) || *pstr == '-' || *pstr == '_' || *pstr == '.' || *pstr == '~')
*pbuf++ = *pstr;
else if (*pstr == ' ')
*pbuf++ = '+';
else
*pbuf++ = '%', *pbuf++ = to_hex(*pstr >> 4), *pbuf++ = to_hex(*pstr & 15);
pstr++;
}
*pbuf = '\0';
return buf;
}
/* Returns a url-decoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
char *url_decode(char *str) {
char *pstr = str, *buf = malloc(strlen(str) + 1), *pbuf = buf;
while (*pstr) {
if (*pstr == '%') {
if (pstr[1] && pstr[2]) {
*pbuf++ = from_hex(pstr[1]) << 4 | from_hex(pstr[2]);
pstr += 2;
}
} else if (*pstr == '+') {
*pbuf++ = ' ';
} else {
*pbuf++ = *pstr;
}
pstr++;
}
*pbuf = '\0';
return buf;
}
