A C++ string parser

Parser.h

#ifndef _PARSER_H
#define _PARSER_H

#include <string>

using namespace std;

void cutstring(string &input, int pos)
{
        string dummy = "";

        for(int i = pos; i < input.length(); i++)
        {
			dummy += input[i];
        }
        input = dummy;
}

string concatenate(string &input)
{
        string ls = "";
        if(input == "")
        {
                return "";
        }
        int size = input.length();
        int cnt = 0;
        int i = 0;
        while(isspace(input[cnt]))
        {
                cnt ++;
                if(cnt == size)
                        return "";
        }
        if(cnt == size)
        {
                return "";
        }
        while(cnt < size)
        {
                if(isspace(input[cnt]))
                        break;
                ls += input[cnt];
                cnt++;
        }
        cutstring(input,cnt);
        return ls;
}
#endif