c++ - 为什么所有cout和cin的“未声明标识符

Question

在我的main.cpp中，所有cout和cin都有错误。

/**
* Description: This program demonstrates a very basic String class.  It creates
* a few String objects and sends messages to (i.e., calls methods on)
* those objects.
*
*/
//#include <iostream>
#include "mystring.h"
//using namespace std;

/* Function Prototypes */

void Display(const String &str1, const String &str2, const String &str3);


/*************************** Main Program **************************/

int main()
{
  String str1, str2, str3;   // Some string objects.
  char s[100];               // Used for input.

  // Print out their initial values...

 cout << "Initial values:" << endl;
 Display(str1, str2, str3);

我的main.cpp无法更改，所以我的问题是，如何解决此错误，我必须在头文件和实现文件中添加什么？

Answer 1

In my main.cpp all of my cout's and cin's have errors.

您只需要 include <iostream>头文件，并使用 std和 cout和 cin:

#include <iostream>
//^^
int main()
{
    std::cout << "Initial values: "<< std::endl;
    //^^
}