/*
革啟部落格，程式袁歡，袁歡的部落格，袁歡部落格
版本：vs2019社群版
功能：計算分段函式*/
#include<stdio.h>
double factorial(int a)
{
    int i;
    double factorial_Value = 1.0;
    for (i = 1; i < a; i++)
    {
        factorial_Value = factorial_Value * i;
    }
    return factorial_Value;
}
void main()
{
    int m = 0, n = 0;
    
 
double factorial_m = 0;
    double factorial_n = 0;
    double factorial_mn = 0;
    double P_mn = 0.0;
    printf("請輸入兩個引數的值：\n");
    printf("m=");
    scanf_s("%d", &m);
    printf("n=");
    scanf_s("%d", &n);
    if (m > n)
    {
        factorial_m = factorial(m);
        factorial_n = factorial(n);
        factorial_mn 
 
= factorial(m - n);
        if (0 == factorial_n || 0 == factorial_mn)
        {
            printf("錯誤，0不能作為除數！\n");
        }
        else
        {
            P_mn = factorial_m / (factorial_n * factorial_mn);
        }
    }
    else
    {
        P_mn = 0;
    }
    printf("計算結果為：");
    printf("P_mn=%f\n
 
", P_mn);
}