Question

我不确定为什么我的程序无法运行。它说User :: receiveMessage和User :: sendMessage必须返回一个值。我很抱歉，我对编程很新。

#include <iostream>
#include <string.h>
#include <cstring>

using namespace std;
class User {
public:
  char username[16];
  char userMotto[64];

public:
  User(char name[16], char motto[64]) {
    strcpy(username, name);
    strcpy(userMotto, motto);
  }

  int sendMessage(const char *messageString, User &otherUser) {
    cout << "\n" << username << " is sending this message: " << messageString;
    otherUser.receiveMessage(messageString);
  }

  int receiveMessage(const char *messageString) {
    cout << endl << username << " received this message: " << messageString;
  }
};

int main() {
  User sender("Bill", "I message, therefore I am");
  char message[64];
  cout << "Enter your Message to Send: ";
  cin >> message;
  User receiver("Ted", "I message, therefore I am");
  sender.sendMessage(message, receiver);
  return 0;
}

Answer 1

我通过clang-format和an online Clang compiler传递了您的代码，这些是错误消息：

prog.cc:20:3: warning: control reaches end of non-void function [-Wreturn-type]
  }
  ^

prog.cc:24:3: warning: control reaches end of non-void function [-Wreturn-type]
  }
  ^

prog.cc:28:15: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
  User sender("Bill", "I message, therefore I am");
              ^

prog.cc:28:23: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
  User sender("Bill", "I message, therefore I am");
                      ^

prog.cc:32:17: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
  User receiver("Ted", "I message, therefore I am");
                ^

prog.cc:32:24: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
  User receiver("Ted", "I message, therefore I am");
                       ^

要修复前两个警告，您需要更改这些功能：

  int receiveMessage(const char *messageString) {
    cout << endl << username << " received this message: " << messageString;
  }

receiveMessage是否需要返回int？如果没有，请将其更改为void返回类型：

void receiveMessage(...

如果确实需要返回int，请在结尾处添加return语句：

  int receiveMessage(const char *messageString) {
    ...
    return 0;
  }

对于其他警告，您可以将char[]全部替换为std::string，但它们并不是那么糟糕。

C4716错误 - 必须返回值

1 个答案: