c ++查找字符串_C ++朋友功能| 查找输出程序| 套装2

c ++查找字符串

Program 1:

程序1：

#include <iostream>
using namespace std;
class Sample1 {
int A, B;
friend class Sample2;
};
class Sample2 {
int X, Y;
public:
Sample2()
{
X = 5;
Y = 5;
}
void fun()
{
Sample1 S;
S.A = 10 * X;
S.B = 20 * Y;
cout << S.A << " " << S.B << endl;
}
};
int main()
{
Sample2 S;
S.fun();
return 0;
}

Output:

输出：

50 100

Explanation:

说明：

Here, we created two classes Sample1 and Sample2, we made Sample2 class as a friend of Sample1 class. Then Sample2 can access the private members of Sample1.

在这里，我们创建了两个类样本1和样本2，我们做了样品2类作为样本1类的朋友。然后Sample2可以访问Sample1的私有成员。

Here, we access the private members A and B of Sample1 class in the member function fun() of Sample2 class and then we set the value to the members and print values.

在这里，我们访问Sample2类的成员函数fun()中Sample1类的私有成员A和B ，然后将值设置为成员并打印值。

Program 2:

程式2：

#include <iostream>
using namespace std;
class Sample1 {
int A, B;
public:
friend class Sample2;
void fun1()
{
Sample2 S;
S.X = 10;
S.Y = 20;
cout << S.X << " " << S.Y << endl;
}
};
class Sample2 {
int X, Y;
public:
friend class Sample1;
Sample2()
{
X = 5;
Y = 5;
}
void fun2()
{
Sample1 S;
S.A = 10 * X;
S.B = 20 * Y;
cout << S.A << " " << S.B << endl;
}
};
int main()
{
Sample2 S;
S.fun();
return 0;
}

Output:

输出：

main.cpp: In member function ‘void Sample1::fun1()’:
main.cpp:12:9: error: ‘Sample2’ was not declared in this scope
Sample2 S;
^~~~~~~
main.cpp:13:9: error: ‘S’ was not declared in this scope
S.X = 10;
^
main.cpp: In function ‘int main()’:
main.cpp:43:7: error: ‘class Sample2’ has no member named ‘fun’; did you mean ‘fun2’?
S.fun();
^~~

Explanation:

说明：

It will generate an error because we are accessing the Sample2 from Sample1 but Sample2 is declared below, so it is not accessible. Then it will generate an error.

因为我们访问来自样本1的样品2，但样品2如下声明，所以它不能访问它会产生一个错误。然后它将产生一个错误。

Program 3:

程式3：

#include <iostream>
class SampleB;
class SampleA {
public:
void show(SampleB&);
};
class SampleB {
private:
int VAL;
public:
SampleB() { VAL = 10; }
friend void SampleA::show(SampleB& x);
};
void SampleA::show(SampleB& B)
{
std::cout << B.VAL;
}
int main()
{
SampleA A;
SampleB OB;
A.show(OB);
return 0;
}

Output:

输出：

Explanation:

说明：

Here, we create two classes SampleA and SampleB. And, we created show() function as a friend of SampleB, then it can access private members of class SampleB.

在这里，我们创建两个类SampleA和SampleB 。并且，我们以SampleB的朋友的身份创建了show()函数，然后它可以访问SampleB类的私有成员。

Then, we defined show() function, where we accessed private member VAL inside function show() of SampleA class and print the value VAL.

然后，我们定义了show()函数，在此我们访问SampleA类的函数show()内部的私有成员VAL并打印值VAL 。