c ++查找字符串
Program 1:
程序1：
#include <iostream>
using namespace std;
class Sample {
int A, B;
friend void fun();
};
void fun()
{
Sample S;
S.A = 10;
S.B = 20;
cout << S.A << " " << S.B << endl;
}
int main()
{
fun();
return 0;
}
Output:
輸出：
10 20
Explanation:
說明：
Here, we created a class Sample that contains private data members A and B.
在這里，我們創建了一個類Sample ，其中包含私有數據成員A和B。
As we know that, we cannot access the private members outside the class. Here, we defined a non-member function as a friend function that can access private members.
眾所周知，我們無法訪問課程之外的私人成員。 在這里，我們將非成員函數定義為可以訪問私有成員的朋友函數。
Then, we set the values into A and B and printed.
然后，將值設置為A和B并打印。
Program 2:
程式2：
#include <iostream>
using namespace std;
class Sample {
int A, B;
void fun();
};
friend void fun()
{
Sample S;
S.A = 10;
S.B = 20;
cout << S.A << " " << S.B << endl;
}
int main()
{
fun();
return 0;
}
Output:
輸出：
main.cpp:9:1: error: ‘friend’ used outside of class
friend void fun()
^~~~~~
main.cpp: In function ‘void fun()’:
main.cpp:13:7: error: ‘int Sample::A’ is private within this context
S.A = 10;
^
main.cpp:5:9: note: declared private here
int A, B;
^
main.cpp:14:7: error: ‘int Sample::B’ is private within this context
S.B = 20;
^
main.cpp:5:12: note: declared private here
int A, B;
^
main.cpp:16:15: error: ‘int Sample::A’ is private within this context
cout << S.A << " " << S.B << endl;
^
main.cpp:5:9: note: declared private here
int A, B;
^
main.cpp:16:29: error: ‘int Sample::B’ is private within this context
cout << S.A << " " << S.B << endl;
^
main.cpp:5:12: note: declared private here
int A, B;
^
Explanation:
說明：
This code will generate an error because we are accessing the private members of class Sample in the function fun() but did not define fun() as a friend within the class. We need to define fun() as a friend inside the class.
該代碼將產生錯誤，因為我們正在訪問fun()函數中的Sample類的私有成員，但未將fun()定義為該類中的朋友 。 我們需要將fun()定義為類中的朋友。
class Sample
{
int A,B;
friend void fun();
};
Program 3:
程式3：
#include <iostream>
using namespace std;
class Sample {
int A, B;
friend void fun();
};
friend void fun()
{
Sample S;
S.A = 10;
S.B = 20;
cout << S.A << " " << S.B << endl;
}
int main()
{
fun();
return 0;
}
Output:
輸出：
main.cpp:9:1: error: ‘friend’ used outside of class
friend void fun()
^~~~~~
Explanation:
說明：
This code will generate an error because we used friend keyword in the definition of the function fun(). We cannot use a friend keyword outside the class.
該代碼將產生錯誤，因為我們在函數fun()的定義中使用了friend關鍵字。 我們不能在課程外使用friend關鍵字。
Program 4:
計劃4：
#include <iostream>
using namespace std;
class Sample1 {
int A, B;
public:
friend class Sample2;
};
class Sample2 {
int X, Y;
void fun1()
{
Sample1 S;
S.A = 10;
S.B = 20;
cout << S.A << " " << S.B << endl;
}
};
int main()
{
Sample2 S;
S.fun1();
return 0;
}
Output:
輸出：
main.cpp: In function ‘int main()’:
main.cpp:27:12: error: ‘void Sample2::fun1()’ is private within this context
S.fun1();
^
main.cpp:14:10: note: declared private here
void fun1()
^~~~
Explanation:
說明：
This code will generate an error, we are accessing the private member function fun1() in the main() function.
此代碼將產生錯誤，我們正在訪問main()函數中的私有成員函數fun1() 。
翻譯自: https://www.includehelp.com/cpp-tutorial/friend-function-find-output-programs-set-1.aspx
c ++查找字符串
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