上机作业2-2，3，4

2分段函数

#include<iostream>
using namespace std;
int main()
{
    double x,y;
    cin>>x;
    if(x>=1)
        {
            y=x-1;
            cout<<y;
        }
    else
    {
        y=1-x;
        cout<<y;
    }
	return 0;

｝

3两点距离

# include<iostream>
# include<cmath>
using namespace std;
int main()
{
 double x1,x2,y1,y2,a,b,c;
 cin>>x1>>x2>>y1>>y2;
 a=(x1-x2)*(x1-x2);
 b=(y1-y2)*(y1-y2);
 c=sqrt(a+b);
 cout<<c<<endl;
}

4自动取款机

# include<iostream>
using namespace std;
int main()
{
    int x,z;
    const int y=199710;
    cin>>x;
    if(x==y)
    {
        cout<<"1.查询\n"<<"2.取款\n"<<"3.存款\n"<<"4.转账\n"<<"0.退出\n";
        cin>>z;
        cout<<"谢谢，"<<"你选择了" <<z<<"号功能";
    }
    else
        cout<<"密码错误";
    return 0;

}