Cracking the Coding Interview 5.2

#include<iostream>
#include<string>
#include<stdlib.h>
using namespace std;

string func(const string &str)
{
    string strInt;
    string strDou;

    string::size_type idx = str.find(‘.‘);    
    if(idx == string::npos)
    {
        strInt = str;
    }
    else
    {
        strInt = str.substr(0,idx);
        strDou = str.substr(idx);
    }

    int intPart = atoi(strInt.c_str());
    double douPart;
    if(!strDou.empty())
    {
        douPart = atof(strDou.c_str());
    }
    else
    {
        douPart = 0.0;
    }

    string strIntB,strDouB;
    while(intPart!=0)
    {
        if((intPart&1)>0)
        {
            strIntB = ‘1‘+strIntB;
        }
        else
        {
            strIntB = ‘0‘+strIntB;
        }
        intPart=intPart>>1;
    }
    while(!(douPart>-10e-15 && douPart<10e-15))
    {
        if(douPart*2>1)
        {
            strDouB = ‘1‘+strDouB;
            douPart = douPart*2-1;
        }

        else if((douPart*2-1)>-10e-15 && (douPart*2-1)<10e-15)
        {
            strDouB = ‘1‘+strDouB;
            break;
        }

        else
        {
            strDouB = ‘0‘+strDouB;
        }
        if(strDouB.size()>32)
        {
            return "ERROR";
        }
    }

    if(strDouB.empty())
    {
        return strIntB;
    }
    else
    {
        return (strIntB+‘.‘+strDouB);
    }
}

int main()
{
    string str("3.75");
    cout<<func(str)<<endl;
    return 0;
}