Return (\r) breaking cout - c++

Question

std::cout prints extra characters in my keyPressed string, probably because of "\r", for example, if keyPressed = "Right arrow", when I press the up arrow, it prints "keyPressed = Up arrowoww", then, when I press right arrow again, it prints "keyPressed = Right arrow" normally again, but if I press any arrow key except "Right arrow" it prints some unwanted extra characters at the end
Error example
Source code:
game.cpp
#include "engine.h"
#include <iomanip>
Engine eng;
int main() {
while (eng.isRunning) {
eng.getInput();
std::cout << std::setw(5);
std::cout << "\r X = " << eng.playerX;
std::cout << "| Y = " << eng.playerY;
std::cout << "| KEY = " << eng.keyPressed;
Sleep(100);
}
return 0;
}
engine.h
#ifndef ENGINE_H
#define ENGINE_H
#include <iostream>
#include <Windows.h>
#include <string>
class Engine {
public:
// Game
bool isRunning = true;
bool gettingInput = true;
// Player
int playerX = 1;
int playerY = 1;
char playerModel = 'P';
// Test / Debug
std::string keyPressed;
// Functions
char getInput() {
// Gets arrow keys states
while (this->gettingInput) {
this->keyPressed = "";
if (GetAsyncKeyState(VK_RIGHT)) {
// Right arrow key
this->playerX++;
this->keyPressed = "Right arrow";
break;
}
else if (GetAsyncKeyState(VK_LEFT)) {
// Left arrow key
this->playerX--;
this->keyPressed = "Left arrow";
break;
}
else if (GetAsyncKeyState(VK_UP)) {
// Up arrow key
this->playerY++;
this->keyPressed = "Up arrow";
break;
}
else if (GetAsyncKeyState(VK_DOWN)) {
// Down arrow key
this->playerY--;
this->keyPressed = "Down arrow";
break;
}
else if (GetAsyncKeyState(VK_END)) {
exit(0);
}
Sleep(255);
}
}
};
#endif
Best / easiest way to fix this?
I searched and tested for 3 days but didn't find anything, please, help me.

Answer 1

Since you're overwriting the previous output, when you print a shorter string the extra characters from the previous output are still displayed. Replace the \r with a \n to see what's actually being output.
You can output some spaces after your key name to overwrite those extra characters with spaces and erase them.

Answer 2

After looking over your provided code I do see a few issues or concerns with the code design: I'll break it down and explain some of the things that I see that could improve the quality of your code. I will start with your main.cpp then move on to your Engine class.
You initially have this:
#include "engine.h"
#include <iomanip>
Engine eng;
int main() {
while (eng.isRunning) {
eng.getInput();
std::cout << std::setw(5);
std::cout << "\r X = " << eng.playerX;
std::cout << "| Y = " << eng.playerY;
std::cout << "| KEY = " << eng.keyPressed;
Sleep(100);
}
return 0;
}
The first main issue that I see is that you have declared Engine eng at the global level. We can fix this by
#include "engine.h"
#include <iostream>
#include <iomanip>
int main() {
Engine eng; // declare it here as the first object in main; now it has local
// scope within main's function and is now in Automatic Storage
// instead of Global Storage.
while( ... ) {
// ....
}
return 0;
};
The next issue starts with while loop's conditional expression in the main function.
You currently have:
while( engine.isRunning ) { //... }
This is okay but this is more of an issue with your Engine class's design. Here you are providing a public member that anyone can access. So let's look at your class declaration/definition; you currently have:
#ifndef ENGINE_H
#define ENGINE_H
#include <iostream>
#include <Windows.h>
#include <string>
class Engine {
public:
// Game
bool isRunning = true;
bool gettingInput = true;
// Player
int playerX = 1;
int playerY = 1;
char playerModel = 'P';
// Test / Debug
std::string keyPressed;
// Functions
char getInput() { // ... }
};
#endif
Here you should protect your data members and have access modifiers functions to them:
#ifndef ENGINE_H
#define ENGINE_H
#include <iostream>
#include <Windows.h>
#include <string>
class Engine {
private:
bool isRunning;
bool gettingInput;
// Player
int playerX;
int playerY;
char playerModel;
// Test / Debug
std::string keyPressed;
public:
Engine() :
isRunning( false ),
isGettingInput( false ),
playerX( 1 ),
playerY( 1 ),
playerModel( 'P' )
{}
void run() { isRunning = true; // set or call other things here... }
// Since we protected our members variables by making them private,
// we now need some access functions to retrieve and modify them.
bool isActive() const { return isRunning; } // make this const so it doesn't change anything
void toggleIsActive() { isRunning = !isRunning; }
bool retrievingInput() const { return isGettingInput; }
void toggleRetrievingInput() { isGettingInput = !isGettingInput; }
int getPlayerX() const { return playerX; }
void setPlayerX( int newX ) { playerX = newX; }
int getPlayerY() const { return playerY; }
void setPlayerY( int newY ) { playerY = newY; }
// set both in one function call
void setPlayerPosition( int newX, int newY ) {
playerX = newX;
playerY = newY;
}
char getPlayerModel() const { return playerModel; }
// don't know if you want to change this: uncomment if you do
// void setPlayerModel( char c ) { playerModel = c; }
std::string& getPressedKey() const { return keyPressed; }
char getInput() { // ... }
};
This should fix the interface design of your class. The only major difference here is that I had set your Boolean member variables to false by default because typically when you first start an Engine it is currently not already running. So to fix this we can call a public run function that will trigger this. So main would look like this instead:
int main () {
Engine eng;
eng.run(); // this now starts the engine sets the flag to true
while (...) { //... }
return 0;
}
However, I have also seen few concerns in your Engine's getInput() function, so let's take a look at it.
char getInput() {
// Gets arrow keys states
while (this->gettingInput) {
this->keyPressed = "";
if (GetAsyncKeyState(VK_RIGHT)) {
// Right arrow key
this->playerX++;
this->keyPressed = "Right arrow";
break;
}
else if (GetAsyncKeyState(VK_LEFT)) {
// Left arrow key
this->playerX--;
this->keyPressed = "Left arrow";
break;
}
else if (GetAsyncKeyState(VK_UP)) {
// Up arrow key
this->playerY++;
this->keyPressed = "Up arrow";
break;
}
else if (GetAsyncKeyState(VK_DOWN)) {
// Down arrow key
this->playerY--;
this->keyPressed = "Down arrow";
break;
}
else if (GetAsyncKeyState(VK_END)) {
exit(0);
}
Sleep(255);
}
}
The first part is the while loop's condition statement and your class's member. Originally you have this set to true by default, yet no where in the code did I see this value being updated. We don't need to change this but the fix is simple now that we have a way to change this member through a public interface call. Since I have made your isGettingInput false by default; you can now set this within this function before you enter the while loop. The only last issue that I see is that when this function is called back in main's while loop; this function never return's a value and the return value is never being used.
As to your actual problem with your bug for cout user : 1201programalarm has pretty much already answered that for you. Just thought I'd help you out a little bit more with your code.