更多"有以下程序#include <iostream>using names"的相关试题:
[单项选择]有以下程序
#include <iostream>
using namespace std;
class sampleprivate:
int x;
public:
sample(int a)
x=a;
friend double square(sample s);
;
double square(sample s) return s. x*s. x;int main( ) sample s1(20),s2(30);
cout<<square(s2)<<end1;
return 0;执行结果是( )。
A. 20
B. 30
C. 900
D. 400