urlencode 질문드립니다.

static char _x2c(char hex_up, char hex_low) 
{
        char digit;
 
        digit = 16 * (hex_up >= 'A' 
                ? ((hex_up & 0xdf) - 'A') + 10 : (hex_up - '0'));
        digit += (hex_low >= 'A' 
                ? ((hex_low & 0xdf) - 'A') + 10 : (hex_low - '0'));
        return (digit);
}
 
char *qURLencode(char *str) 
{
        char *encstr, buf[2+1];
        unsigned char c;
        int i, j;
 
        if(str == NULL) return NULL;
        if((encstr = (char *)malloc((strlen(str) * 3) + 1)) == NULL) 
                return NULL;
 
        for(i = j = 0; str[i]; i++) 
        {
                c = (unsigned char)str[i];
                if((c >= '0') && (c <= '9')) encstr[j++] = c;
                else if((c >= 'A') && (c <= 'Z')) encstr[j++] = c;
                else if((c >= 'a') && (c <= 'z')) encstr[j++] = c;
                else if((c == '@') || (c == '.') || (c == '/') || (c == '\\')
                        || (c == '-') || (c == '_') || (c == ':') ) 
                        encstr[j++] = c;
                else 
                {
                        sprintf(buf, "%02x", c);
                        encstr[j++] = '%';
                        encstr[j++] = buf[0];
                        encstr[j++] = buf[1];
                }
        }
        encstr[j] = '\0';
 
        return encstr;
}