C语言掷骰子程序

//diceroll.h
extern int roll_count;

int roll_n_dice(int dice, int sides);

/* diceroll.c -- dice role simulation */
/* compile with mandydice.c           */
#include "diceroll.h"
#include <stdio.h>
#include <stdlib.h>           /* for library rand()   */

int roll_count  = 0;          /* external linkage     */

static int rollem(int sides)  /* private to this file */
{
    int roll;

    roll = rand() % sides + 1;
    ++roll_count;             /* count function calls */

    return roll;
}

int roll_n_dice(int dice, int sides)
{
    int d;
    int total = 0;
    if (sides < 2)
    {
        printf("Need at least 2 sides.\n");
        return -2;
    }
    if (dice < 1)
    {
        printf("Need at least 1 die.\n");
        return -1;
    }

    for (d = 0; d < dice; d++)
        total += rollem(sides);

    return total;
}