Recursive martini class

martini.c

// A cool way to draw a martini glass; this was on the final of CS 115 at U of I

#include <stdio.h>

void drawcup(int N, int offset) {

    // base case
    if (offset > N)
        return;

    int i;
    for (i = 0; i < offset; i ++)
        printf(" ");
    for (/* i = offset */; i < N; i++)
        printf("*");
    printf("\n");

    // recursive case
    drawcup(N - 1, offset + 1);
}

void draw(int N) {

    // "cup"
    drawcup(N, 0);

    // "stem"
    int i, j;
    int halfset = N / 2; // truncated
    for (j = 0; j < halfset; j++)  {
        for (i = 0; i < halfset; i++)
            printf(" ");
        printf("*\n");
    }

    // "base"
    for (i = 0; i < N; i++)
        printf("*");
    printf("\n");
}

int main(int argc, char* argv[]) {

    if (argc != 2) {
        fprintf(stderr, "USAGE: martini N\n");
        return 1;
    }

    int N = atoi(argv[1]);

    if (N % 2 != 1) {
        fprintf(stderr, "N must be odd\n");
        return 2;
    }

    // git 'er dun
    draw(N);
}