draw square interactively

square-interactive.c

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

int sq(int w, int h) {
    int x, y = 1;
    while (y <= h) {
        x = 1;
        while (x <= w) {
            if ((x == 1 || x == w) && (y == 1 || y == h)) {
                addch('o');
            } else if (x == 1 || x == w) {
                addch('|');
            } else if (y == 1 || y == h) {
                addch('-');
            } else {
                addch(' ');
            }
            ++x;
        }
        addch('\n');
        ++y;
    }
}

int main() {
    int key;
    int w = 1, h = 1;
    int i;
    int redraw = true;

    initscr();
    noecho();
    curs_set(0);
    nodelay(stdscr, true);
    keypad(stdscr, true);
    while (true) {
        if (redraw) {
            move(0, 0);
            printw("sq(%u, %u)\n", w, h);
            sq(w, h);
            refresh();
        } else {
            timeout(1000);
        }
        switch (key = getch()) {
            case KEY_UP:
                if (h < 10) {
                    ++h;
                    redraw = true;
                }
                break;
            case KEY_DOWN:
                if (h > 1) {
                    move(h, 0);
                    clrtoeol();
                    --h;
                    redraw = true;
                }
                break;
            case 'w':
            case 'W':
                if (w < 30) {
                    ++w;
                    redraw = true;
                }
                break;
            case 's':
            case 'S':
                if (w > 1) {
                    --w;
                    i = 0;
                    while (i < h) {
                        move(i, w);
                        clrtoeol();
                        ++i;
                    }
                    redraw = true;
                }
                break;
            case 'q':
            case 'Q':
                return 0;
        }
    }
}