How to implement a getchar or getch function using C++ libraries.

There is no getchar() function in C++ as it's not in iostream.h library. We can implement a getchar() function using some bash commands to implement the function under GNU/Linux. In Windows you can import the library conio.h so you don't have this problem.

Here is a sample code of getch() or getchar() function development:

For example, we create a file named nstdio.h which contains the function getch().

#include <iostream>
#include <string>
#include <sstream>
#include <fstream>
#include <cstdlib>

using namespace std;

static bool isGenerated = false;

const string readCharScript[7] = {"#!/bin/sh" ,
  "tput smso",
  "tput rmso",
  "oldstty=`stty -g`",
  "stty -icanon min 1 time 0",
  "dd bs=1 count=1 of=output >/dev/null 2>&1",
  "stty \"$oldstty\"" };

void resetOutputFile() {
  ofstream outputFile( "output", fstream::out );
    outputFile << "$";
  outputFile.close(); 
}
  
void GenereFile() {
  resetOutputFile();
  ofstream readFile( ".readone", fstream::out );
  for ( int i = 0; i < 7; i++ )
    readFile << readCharScript[i] << endl;
  readFile.close();
  system("chmod ugo+x .readone");
  isGenerated = true;
}

char getch() { 
  if (!isGenerated)
    GenereFile();
  system("./.readone");
  const int EOL = '$';
  char ch;
  ifstream file("output", fstream::in);
  while (ch == EOL)
    file >> ch;
  file.close();
  resetOutputFile();
  return ch;
}

A file to test the getch() function called test.cpp.

#include <iostream>
#include "nstdio.h"


using namespace std;

int main() {
  char ch = getch();
  if (ch == '\n')
    cout << "Se pulsó intro" << endl;
  else
    cout << endl << "El caracter es: " << ch << endl;
  return 0;
} 

As you can see I didn't use objects, but you can encapsulate the methods in a class. The important thing is that I only use C++ libraries.

Furthermore, don't forget that C++ is a multiparadigm language, so you can use both, OO and procedural programming.

Have a nice programming!