is it possible to grab data from an .exe file in c++? - c++

Question

I am new at C/C++,
So basically I want to call an .exe file that displays 2 numbers and be able to grab those two numbers to use them in my code.
To call the .exe file I've used the system command, but I am still not able to grab those two numbers that are displayed by the .exe file
char *files = "MyPath\file.exe";
system (files);

Answer 1

I think this is better aproach:
Here you just create new process, and you read data that process gives you. I tested this on OS X 10.11 with .sh file and works like a charm. I think that this would probably work on Windows also.
FILE *fp = popen("path to exe","r");
if (fp == NULL)
{
std::cout << "Popen is null" << std::endl;
}else
{
char buff[100];
while ( fgets( buff, sizeof(buff), fp ) != NULL )
{
std::cout << buff;
}
}

Answer 2

You need to escapr back slashes in C++ string literals so:
// note the double "\\"
char* files = "MyPath\\file.exe";
Or just use forward slashes:
char* files = "MyPath/file.exe";
Its not very efficient but one thing you can to with std::system is redirect the output to a file and then read the file:
#include <cstdlib>
#include <fstream>
#include <iostream>
int main()
{
// redirect > the output to a file called output.txt
if(std::system("MyPath\\file.exe > output.txt") != 0)
{
std::cerr << "ERROR: calling system\n";
return 1; // error code
}
// open a file to the output data
std::ifstream ifs("output.txt");
if(!ifs.is_open())
{
std::cerr << "ERROR: opening output file\n";
return 1; // error code
}
int num1, num2;
if(!(ifs >> num1 >> num2))
{
std::cerr << "ERROR: reading numbers\n";
return 1; // error code
}
// do something with the numbers here
std::cout << "num1: " << num1 << '\n';
std::cout << "num2: " << num2 << '\n';
}
NOTE: (thnx #VermillionAzure)
Note that system doesn't always work everywhere because unicorn
environments. Also, shells can differ from each other, like cmd.exe
and bash. – VermillionAzure
When using std::system the results are platform dependant and not all shells will have redirection or use the same syntax or even exist!