20 Lines program crashes continue

[4i67ko23]

Hi there,
I'm learning to work with functions,, it isn't my first work, my second.
It crashes continue without reason. It's really simple, so why crashing?

#include <windows.h>
#include <algorithm>
#include <iostream>
#include <fstream>
#include <string>
//-----------------------------------------------------------
using namespace std;
//-----------------------------------------------------------
string readfile(string IN_FILE_NAME)
{ 
    string line;
    ifstream myfile (IN_FILE_NAME.c_str());
    if (myfile.is_open())
    {
        while ( myfile.good() )
        {
            getline (myfile,line);
            cout << line << endl;
        }
        myfile.close();
    }
    else cout << "Unable to open file"; 
}
//-----------------------------------------------------------
int main()
{
    //writefile("TEST123", "mathijs_text_1");//1
    readfile("abc123.txt");
    Sleep(10000);
}

[Moschops]

The function readfile is expected to return a string. You are not returning a string.

The compiler doesn't care. It will still treat whatever data is in the place where returned variables go as a string. This means it is treating some random data as a string. When the time comes to destruct that string, it is trying to call a string destruction function on something that is not a string. This is very, very bad.

Your compiler ideally should warn you about this sort of thing. If it does not, you need to turn up the warning level. The g++ compiler says this, for example:

In function ‘std::string readfile(std::string)’:
 warning: no return statement in function returning non-void [-Wreturn-type]

Clang says this:

 warning: control reaches end of non-void function [-Wreturn-type]

Turn up warnings on your compiler, and listen to what they say.

[vlad from moscow]

Your ptogram has underfined behavior because function readfile has no return value thoug it is declared that is returns an object of type std::string. Change its declaration the following way

void readfile( const string &IN_FILE_NAME )

[4i67ko23]

Edit;
Already found!
I wasn't forget to add "return (line)" but I had to!
Problem fixed

[4i67ko23]

Hi, I see your commend now, we posted all at the same time :D
the problem was "return"