comparing characters in a string

[ikhram]

Hello coders

The code below is supposed to take first 2 characters from the main string and put it into string twochars the next 2 characters go into another string secondtwochars. If the charcters of the temp strings are equal it will increment a counter and get the next two string of 2 characters each until the main string is over but it is giving bogus data
eg: string : efef3030 should be ef023002 but its not please help

string comparision(string hextext) {
    //string hextext = "";
    int counter;
    int length = hextext.size();
    std::string twochars = "";
    std::string secondtwochars = "";
    trace() << "Input : " << hextext ; 
    string runlengthengthcoding = "";
 
 
    /*for(int w=0;w<52;w++){
         
        if(temphexholder[0] == databytes[w]){
            counter++;      
        }
        if(temphexholder[0] != databytes[w]){
            runlengthengthcoding += databytes[w] + counter; 
            counter = 0;
            temphexholder[0] = databytes[w];
        }
         
    } */
    for(int i=0 ; i< length; i+=4)
        {
         
        twochars = hextext.substr(i, 2) ;
         
        for(int k=2 ; k< length; k+=4)
        {
         
        secondtwochars = hextext.substr(k, 2) ;
         
         
        if(twochars == secondtwochars){
             
            counter++;  
             
        }
        if(twochars != secondtwochars){
            string counters = to_string(counter);
            runlengthengthcoding += twochars + counters;    
            counter = 0;
             
        } 
        }
        }
     
    return runlengthengthcoding; 
} 
 
int main (){
string t = "30304040";
cout << comparison(t); 
}

[VictorN]

What is temphexholder?

[2kaud]

What debugging of the code has been done? Has the debugger been used to trace through the code line by line and the contents of the variables watched? If not, now's the time to learn how to use the debugger. if yes, where did the code deviate from that expected from the program design?