Blank Terminal Screen When Running Curses-Based Snake Game

Question

I am currently working on a simple snake game in C using the curses library. However, when I compile and execute the code to test if the snake marked 'S' would move, the terminal only displays a blank screen. I'm not sure what is causing this issue and I would like to fix it first.
So here is the code:

#include <stdio.h>
#include <stdlib.h>
#include <curses.h>
#include <unistd.h>

/* Define constants for height and width of the rectangle */
#define HEIGHT 20
#define WIDTH 60

/* Variables */
int gameover, x, y, fruitx, fruity, flag;

/* Function to position the fruit */
void position()
{
    gameover = 0;
    x = HEIGHT/2;
    y = WIDTH/2;
    fruitx = rand() % HEIGHT;
    fruity = rand() % WIDTH;
}

/* Function to draw a rectangle with specified height and width */
void boundary(int h, int w)
{
    int i, j;
    for (i = 0; i <= h; i++) /* Rows */
    {
        for (j = 0; j <= w; j++) /* Columns */
        {
            if (i == 0 || i == h || j == 0 || j == w)
            {
                printf("#");
            }
            else
            {
                if (i == x && j == y)
                {
                    printf("S");
                }
                else if (i == fruitx && j == fruity)
                {
                    printf("F");
                }
                else
                {
                    printf(" ");
                }
            }
        }
        printf("\n");
    }
}

/* Set movement */
void keyboard()
{
    int ch;

    switch(getch())
    {
    case KEY_UP:
        flag = 1;
        break;
    case KEY_DOWN:
        flag = 2;
        break;
    case KEY_RIGHT:
        flag = 3;
        break;
    case KEY_LEFT:
        flag = 4;
        break;
    }
    
    if (x < 0 || x >= HEIGHT || y < 0 || y >= WIDTH)
    {
        gameover = 1;
    }
}

/* Commands and logic of the program */
void logic()
{
    switch(flag)
    {
        case 1:
            y--;
            break;
        case 2:
            y++;
            break;
        case 3:
            x++;
            break;
        case 4:
            x--;
            break;
    }
}

int main() {
    // Initialize curses
    initscr();
    raw();
    keypad(stdscr, TRUE);
    noecho();
    curs_set(FALSE);

    // Game loop
    while (!gameover)
    {
        clear(); // Clear the screen
        boundary(HEIGHT, WIDTH); // Draw the game boundary and snake
        keyboard(); // Handle keyboard input
        logic(); // Update snake position
        refresh(); // Refresh the screen

        // Add a small delay for smooth movement
        //usleep(100000);
    }

    // Clean up curses
    endwin();

    return 0;
}

I compiled it using:

gcc snake.c -o snake -lncurses

What could be causing the blank terminal screen issue when running my C code with the curses library? Are there any common mistakes or additional steps I need to take to properly display the snake game?

Any insights, suggestions, or guidance would be greatly appreciated. Thank you in advance for your help!

Have you tried to [*debug*](https://ericlippert.com/2014/03/05/how-to-debug-small-programs/) your program? For example to use a [*debugger*](https://stackoverflow.com/questions/25385173/what-is-a-debugger-and-how-can-it-help-me-diagnose-problems) to step through the code line by line, to see what really happens? — Some programmer dude, Aug 06 '23 at 15:46

score 0 · Accepted Answer · answered Aug 06 '23 at 19:15

In general, you shouldn't mix stdio (printf()) with curses. If you change the printf calls to printw(), the square will be rendered. (I'd also suggest replacing the usleep() delay, if it were uncommented, with an equivalent call to curses' own napms() function (just divide the parameter by 1000).)

Blank Terminal Screen When Running Curses-Based Snake Game

1 Answers1