Compiling Multiple Files

The file below contains only the main function, not userInputNum or printNum.

<aside> 💡

We don’t actually need to include the #include <iostream> since the main function doesn’t actually use anything from that library. All our input and output are implemented in the input.cpp and print.cpp files, which are linked via header files into main.

</aside>

#include <iostream>  // directs to the standard library
using namespace std;
#include "input.h"  // searches for the file in the same directory
#include "print.h"

int main(){
	int x;
	x = userInputNum();
	printNum(x);
	return 0;
}

We have to include 4 total files to make the original main.cpp function work:

• an input.h header file for the input function
• a print.h header file for the print function
• the input.cpp function implementation file
• the print.cpp function implementation file

int userInputNum()

void printNum(int)

#include "input.h"
#include <iostream>
using namespace std;

intUserInput(){
	// function implementation
}

#include "print.h"
#include <iostream>
using namespace std;

void printNum(){
	// function implementation
}

Compilation

To compile all of these files with one command, we do the following:

• Use the g++ compiler command
• List all the source files
• Use the flag output flag -o
• Specify the executable file name

g++ main.cpp input.cpp print.cpp -o main