Functions to encode and decode strings to be valid URL ones

urlencode.cpp

/*
 * urlencode.c
 *
 * Based on code from http://www.zedwood.com/article/111/cpp-urlencode-function
 *
 *  Created on: 21/06/2012
 *      Author: piranna
 */

#include "urlencode.hpp"

#include <stdlib.h>


//based on javascript encodeURIComponent()
string urlencode(const string &c)
{

    string escaped="";

    for(unsigned int i=0; i<c.length(); i++)
        if((48 <= c[i] && c[i] <= 57)   //0-9
        || (65 <= c[i] && c[i] <= 90)   //abc...xyz
        || (97 <= c[i] && c[i] <= 122)  //ABC...XYZ
        || c[i]=='~' || c[i]=='!' || c[i]=='*'
        || c[i]=='(' || c[i]==')' || c[i]=='\'')
        {
            escaped.append(&c[i], 1);
        }
        else
        {
            escaped.append("%");
            escaped.append(char2hex(c[i]));  // converts char 255 to string "ff"
        }

    return escaped;
}

string urldecode(const string &c)
{

    string result="";

    for(unsigned int i=0; i<c.length(); i++)
    {
    	if(c[i] == '%')
    	{
    		// converts string "ff" to char 255
    		char ret = hex2char(c.substr(i+1, 2));
            result.append(&ret, 1);
            i += 2;
    	}
    	else
            result.append(&c[i], 1);
    }

    return result;
}


string char2hex( char dec )
{
    char dig1 = (dec&0xF0)>>4;
    char dig2 = (dec&0x0F);

    if(dig1 >= 0)
    {
        if(dig1 <= 9)       //0,48inascii
        	dig1 += 48;
        else if(dig1 <= 15) //a,97inascii
        	dig1 += 97-10;
    }

    if(dig2 >= 0)
    {
        if(dig2 <= 9)
        	dig2 += 48;
        else if(dig2 <= 15)
        	dig2 += 97-10;
    }

    string r;
    r.append(&dig1, 1);
    r.append(&dig2, 1);
    return r;
}

char hex2char(string hex)
{
	char result = strtoul(hex.c_str(), NULL, 16);
	return result;
}