draw_box.c

// Program - Output a box with given width and height (Box drawn with *)
#include <stdio.h>

void draw_box (unsigned int width, unsigned int height)
{
    // Output the top of the box with "width" asterisks
    for(unsigned int i = 0 ; i < width ; ++i)
        printf("*");
    // Output height-2 rows of "width" characters with * at each end and spaces inside
    for(unsigned int j = 0 ; j < height - 2 ; ++j)
    {
        printf("\n*"); // First asterisk
        // Next draw the spaces
        for(unsigned int i = 0 ; i < width - 2 ; ++i)
            printf(" ");
        printf("*"); // Last asterisk
    }
    // Output the bottom of the box
    printf("\n"); // Start on newline
    for(unsigned int i = 0 ; i < width ; ++i)
        printf("*");
    printf("\n"); // Newline at end of last line
}


int main (void)
{
    const unsigned int MIN_SIZE = 3; // Minimum width and height values
    unsigned int width = 0;
    unsigned int height = 0;
    // Read in required width and height
    printf("Enter values for the width and height (minimum of %u):", MIN_SIZE);
    scanf("%u%u", &width, &height);

    // Validate width and height values
    if(width < MIN_SIZE)
    {
        printf("\nWidth value of %u is too small. Setting it to %u.", width, MIN_SIZE);
        width = MIN_SIZE;
    }
    if(height < MIN_SIZE)
    {
        printf("\nHeight value of %u is too small. Setting it to %u.", height, MIN_SIZE);
        height = MIN_SIZE;
    }
    draw_box (width, height);   // Calling the function
    return 0;
}