将几个程序定义为函数，并在main函数中调用

Question

用到switch case 语句
定义和声明两者如何运用
函数的调用如何操作

Answer 1

运行结果：

代码如下：

#include <iostream>
#include <string>
using namespace std;
void fun1()
{
    int zm=0,kg=0,sz=0,qt=0;
    char buf[100];
    int i=0;
    cin.sync();
    cin.clear();
    cout <<"请输入字符串"<<endl;
    cin.getline(buf,100);
    while(buf[i])
    {
        if((buf[i]>='a' && buf[i]<='z') || (buf[i]>='A' && buf[i]<='Z') )
            zm++;
        else if(buf[i]>='0' && buf[i]<='9')
            sz++;
        else if(buf[i]==' ')
            kg++;
        else
            qt++;
        i++;
    }
    cout <<"字母有："<<zm<<"个"<<endl;
    cout <<"空格有："<<kg<<"个"<<endl;
    cout <<"数字有："<<sz<<"个"<<endl;
    cout <<"其他有："<<qt<<"个"<<endl;
}

void fun2()
{
    int i,fz=2,fm=1,t;
    double s=0;
    for(i=1;i<=20;i++)
    {
        cout <<fz<<"/"<<fm;
        s += 1.0*fz/fm;
        t = fz;
        fz = fz+fm;
        fm = t;
        if(i<20)
            cout <<"+";
    }
    cout << "="<<s<<endl;
}

void fun3()
{
    long long s = 0;
    long long r = 1;
    int n;
    cin >> n;

    for(int i=1;i<=n;i++)
    {
        cout <<i<<"!";
        r*=i;
        s += r;
        if(i<n)
            cout <<"+";
    }
    cout <<"="<<s<<endl;
}

int main()
{
    int op;
    while(1)
    {
        cout <<"1.功能1"<<endl;
        cout <<"2.功能2"<<endl;
        cout <<"3.功能3"<<endl;
        cout <<"0.退出"<<endl;
        cout <<"请选择：";
        cin >> op;
        switch(op)
        {
        case 1:
            fun1();
            break;
        case 2:
            fun2();
            break;
        case 3:
            fun3();
            break;
        case 0:
            return 0;
        }
    }
    return 0;
}