atof(bal.c_str());

#include <iostream>
#include <iomanip>
#include <string>
#include <cstdlib>
 
int main()
{
    std::string s("500.00");
 
    std::cout << std::fixed << std::setprecision(2)
              << std::atof(s.c_str()) << '\n';
}

float tt = atof(bal.c_str());
cout << tt;

#include<sstream>
#include<string>
using namespace std;
int main(){
   stringstream converter;
   string str= "3.14";
   converter << str ;  //put in string 
   float PI = 0;
   converter >> PI; //put out float
 return 0;
}