函数的参数的默认值

A  default argument shall not be redefined by a later declaration (not even to the same value)

#include<iostream>
using namespace std;

void print(double area = 2);

int main(){
print();
print(4);
system("pause");
return 0;
}

void print(double area = 1){
cout<<area;
}

上面代码只能修改成下面的样子才可以：
#include<iostream>
using namespace std;

void print(double area = 2);

int main(){
print();
print(4);
system("pause");
return 0;
}

void print(double area){
cout<<area;
}