Continuous keyboard input in C - c++

Question

I am creating a console application in C. This is a game in which characters are falling down and user has to press that specific key on the keyboard. I don't know how to detect which key is pressed by the user without pausing the falling characters. When I use scanf the Program waits for input and everything pauses.
Please help me soon!

Answer 1

There is a function called kbhit() or _kbhit it is in the <conio.h> library it returns true or false depending whether a key was hit. So you can go with something like this:
while (1){
if ( _kbhit() )
key_code = _getch();
// do stuff depending on key_code
else
continue;
Also use getch() or _getch which reads a character directly from the console and not from the buffer. You can read more about conio.h functions here they might be very useful for what you want to do.
Note: conio.h is not a standard library and implementations may vary from compiler to compiler.

Answer 2

You may probably look for ncurses
ncurses (new curses) is a programming library that provides an API
which allows the programmer to write text-based user interfaces in a
terminal-independent manner. It is a toolkit for developing "GUI-like"
application software that runs under a terminal emulator.
Also check C/C++: Capture characters from standard input without waiting for enter to be pressed
#include <conio.h>
if (kbhit()!=0) {
cout<<getch()<<endl;
}

Answer 3

I think this might be the non-blocking keyboard input you are looking for.
void simple_keyboard_input() //win32 & conio.h
{
if (kbhit())
{
KB_code = getch();
//cout<<"KB_code = "<<KB_code<<"\n";
switch (KB_code)
{
case KB_ESCAPE:
QuitGame=true;
break;
}//switch
}//if kb
}//void
And as for the characters falling down.. here you go.
Code for if you are on Windows:
/* The Matrix falling numbers */
#include <iostream>
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <conio.h>
using namespace std;
#define KB_UP 72
#define KB_DOWN 80
#define KB_LEFT 75
#define KB_RIGHT 77
#define KB_ESCAPE 27
#define KB_F8 66
/* Variables*/
char screen_buffer[2000]={' '};
int y_coord[2000]={0};
int x=0, y=0,dy=0;
int XMAX=77;
int YMAX=23;
int KB_code=0;
bool QuitGame=false;
int platformX=35, platformY=23;
/* function prototypes*/
void gotoxy(int x, int y);
void clrscr(void);
void setcolor(WORD color);
void simple_keyboard_input();
void draw_falling_numbers();
void draw_platform();
/* main */
int main(void)
{
/* generate random seed */
srand ( time(NULL) );
/* generate random number*/
for(int i=0;i<XMAX;i++) y_coord[i]= rand() % YMAX;
while(!QuitGame)
{
/* simple keyboard input */
simple_keyboard_input();
/* draw falling numbers */
draw_falling_numbers();
}
/* restore text color */
setcolor(7);
clrscr( );
cout<<" \n";
cout<<" \nPress any key to continue\n";
cin.ignore();
cin.get();
return 0;
}
/* functions */
void draw_falling_numbers()
{
for(x=0;x<=XMAX;x++)
{
/* generate random number */
int MatixNumber=rand() % 2 ;
/* update falling number */
y_coord[x]=y_coord[x]+1;
if (y_coord[x]>YMAX) y_coord[x]=0;
/* draw dark color */
setcolor(2);
gotoxy(x ,y_coord[x]-1); cout<<" "<<MatixNumber<<" ";
/* draw light color */
setcolor(10);
gotoxy(x ,y_coord[x]); cout<<" "<<MatixNumber<<" ";
}
/* wait some milliseconds */
Sleep(50);
//clrscr( );
}
void draw_platform()
{
setcolor(7);
gotoxy(platformX ,platformY);cout<<" ";
gotoxy(platformX ,platformY);cout<<"ÜÜÜÜÜÜ";
setcolor(7);
Sleep(5);
}
void simple_keyboard_input()
{
if (kbhit())
{
KB_code = getch();
//cout<<"KB_code = "<<KB_code<<"\n";
switch (KB_code)
{
case KB_ESCAPE:
QuitGame=true;
break;
case KB_LEFT:
//Do something
platformX=platformX-4;if(platformX<3) platformX=3;
break;
case KB_RIGHT:
//Do something
platformX=platformX+4;if(platformX>74) platformX=74;
break;
case KB_UP:
//Do something
break;
case KB_DOWN:
//Do something
break;
}
}
}
void setcolor(WORD color)
{
SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),color);
return;
}
void gotoxy(int x, int y)
{
static HANDLE hStdout = NULL;
COORD coord;
coord.X = x;
coord.Y = y;
if(!hStdout)
{
hStdout = GetStdHandle(STD_OUTPUT_HANDLE);
}
SetConsoleCursorPosition(hStdout,coord);
}
void clrscr(void)
{
static HANDLE hStdout = NULL;
static CONSOLE_SCREEN_BUFFER_INFO csbi;
const COORD startCoords = {0,0};
DWORD dummy;
if(!hStdout)
{
hStdout = GetStdHandle(STD_OUTPUT_HANDLE);
GetConsoleScreenBufferInfo(hStdout,&csbi);
}
FillConsoleOutputCharacter(hStdout,
' ',
csbi.dwSize.X * csbi.dwSize.Y,
startCoords,
&dummy);
gotoxy(0,0);
}