c++ tron 2d array repeating - c++

Question

I am trying to get a trail to appear behind the player bike but for some reason instead of a "x" appearing behind the player every time it moves, the player would actually duplicate itself. It sounds a little confusing but you should compile this code yourself and see what i mean. What I am trying to do is just have a trail of "x" behind the player instead of the player leaving a trail of "P". thanks
#include <iostream>
#include "windows.h"
#include <conio.h>
#include <ctime>
using namespace std;
//prototype functions used
void DisplayMap();
void PlayerBike();
void setCursorTo();
void SetBike();
//global variables that will be used by different functions
int PlayerX = 10;
int PlayerY = 70;
bool GameOver = false;
const int H = 25; // const variable so it doesnt change size
const int W = 82;// const variable so it doesnt change size
char Map[H][W]; // char map with HxW
char trail = 'x'; // this is where the trail is initialized as a *
int main()
{
SetBike();
DisplayMap();
while (GameOver == false){
setCursorTo();
PlayerBike();
} // end while loop
return 0;
}//end main
void DisplayMap(){ // display map function
for(int i = 0; i < H; i++ ){
for(int j = 0; j < W; j++){
if(i == 0 || i == 24 || j == 0 || j == 81 ){ Map[i][j] = 'x';} // characters in row 24x81 are changed to x
cout << Map[i][j]; // output map
} // end for loop
cout << "\n"; // create new line to output the map correctly
} //end for loop
} // end DisplayMap function
void SetBike(){
Map[PlayerX] [PlayerY] = 'P';
}
void PlayerBike(){
Map[PlayerY][PlayerX]= trail; // I would like this trail to repeat behind the player but it does not appear at all.
if (kbhit()) {// get user key input
char GetCh = getch(); // GetCh equal to the button the user presses
if (GetCh == 'w'){PlayerX = PlayerX - 1; Trailx = Trailx -1;}
else if (GetCh == 's'){PlayerX = PlayerX +1; Trailx = Trailx +1;}
else if (GetCh == 'd'){PlayerY = PlayerY +1;}
else if (GetCh == 'a'){PlayerY = PlayerY - 1;}
}// end kbhit
}// end PlayerBike function
void setCursorTo() // stops constant flashing on the map
{
HANDLE handle;
COORD position;
handle = GetStdHandle(STD_OUTPUT_HANDLE);
position.X = 0;
position.Y = 0;
SetConsoleCursorPosition(handle, position);
}

Answer 1

Your DisplayMap function is flawed.
First, it seems you are not only displaying the map, you are also actively modifying it. Put the drawing-a-border into a separate initMap function, which also zeros out all other positions with a space (it seems you didn't do that yet, so perhaps that is where it goes wrong). You only need to call initMap once.
Next, do not draw the player P in the DisplayMap function. Draw this once, before entering the game loop. Then: if the user pressed a valid move key,
put an x on the player's position
update player position
put a P on the new position
redraw the screen by calling DisplayMap
and you'll see the trail stays put.
Possible refinements: before accepting a 'move' command by updating the position, check if the map contains a space or something else. If it contains a space, you can execute the move; if not, play an explosion animation (*oO*+.). Also, consider looking up the switch statement in your favourite C reference, to avoid endless long sequences of if..else.