C4716錯誤-必須返回一個值

Question

我不確定為什么我的程序無法運行。 就是說User :: receiveMessage和User :: sendMessage必須返回一個值。 抱歉，我是編程新手。

#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

我通過clang格式和在線Clang編譯器傳遞了您的代碼，這些是錯誤消息：

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");
                       ^

要修復前兩個警告，您需要更改這些功能：

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

receiveMessage是否需要返回一個int ？ 如果不是，請將其更改為void返回類型：

void receiveMessage(...

如果確實需要返回一個int ，則在最后添加一個return語句：

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

對於其他警告，您可以在整個過程中用std::string替換char[] ，但還不錯。