How to do a true strtoul? Wont intake an actual string

Question

Having an issue inputting an ACTUAL string to strtuol. The input string SHOULD be an unsigned binary value of 32 bits long.

Obviously, there is in issue with InputString = apple; but I'm not sure how to resolve the issue. any thoughts? This shouldnt be that difficult. not sure why I'm having such a hard time with it.

Thanks guys.

#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main()
{
    char InputString[40];
    char *pEnd = NULL;          // Required for strtol()
    string apple = "11111111110000000000101010101000";
    //cout << "Number? ";
    //cin >> InputString;
    InputString = apple;
    unsigned long x = strtoul(InputString, &pEnd, 2);     // String to long

    cout << hex << x << endl;
    return 1;
}

Answer 1

Include :

#include<cstdlib> // for strtol()
#include<cstring> // for strncpy()

and then

 strncpy(InputString ,apple.c_str(),40); 
                            ^
                            |
                            convert to C ctring 

Or simply,

unsigned long x = strtoul(apple.c_str(), &pEnd, 2);

Answer 2

A better approach would be to avoid the legacy-C functions and use the C++ standard functions:

string apple = "11111111110000000000101010101000";
unsigned long long x = std::stoull(apple, NULL, 2); // defined in <string>

NOTE: std::stoull will actually call ::strtoull internally, but it allows you to just deal with the std::string object instead of having to convert it to a C-style string.