Question

我只需要帮助完成这项任务。我必须重新定义运算符以使用字符串。我从==运算符开始，我在头文件中声明它，但是当我在cpp文件中定义函数时，它说它与声明的函数不兼容。这可能是一个愚蠢的错误，我有时候并不理解这一点。

string.h头文件

    #pragma once

    #include <iostream>
    #include <string>
    using namespace std;

    #define NOT_FOUND -1

   // C++ String class that encapsulates an ASCII C-string
class String
{
 public:
// Default constructor
String();

// MUST HAVE: Copy-constructor that performs deep copy
String(const String& source);

// Init-constructor to initialize this String with a C-string
String(const char* text);

// Init constructor, allocates this String to hold the size characters
String(int size);

// Destructor
~String();

bool& compareTo(const String& cmp1);
// Assignment operator to perform deep copy
String& operator = (const String& source);

// Assignment operator to assign a C-string to this String
String& operator = (const char* text);

// Returns a reference to a single character from this String
char& operator [] (int index) const;

// Comparison operators
bool operator == (const String& compareTo) const;

string.cpp文件

    #include "string.h"
#include <string>
#include <sstream>

using namespace std;

// Default constructor
String::String()
{
Text = NULL;
}

// MUST HAVE: Copy-constructor that performs deep copy
String::String(const String& source)
{
Text = NULL;
// Call the assignment operator to perform deep copy
*this = source;
}

// Init-constructor to initialize this String with a C-string
String::String(const char* text)
{
Text = NULL;
// Call the assignment operator to perform deep copy
*this = text;
}

// Init constructor, allocates this String to hold the size characters
String::String(int size)
{
Text = new char[size];
}

// Destructor
String::~String()
{
delete[] Text;
}

// Assignment operator to perform deep copy
String& String::operator = (const String& source)
{  
// Call the other assigment operator to perform deep copy
*this = source.Text;
return *this;
}

// Assignment operator to assign a C-string to this String
String& String::operator = (const char* text)
{
// Ddispose of old Text
delete[] Text;

// +1 accounts for NULL-terminator
int trueLength = GetLength(text) + 1;

// Dynamically allocate characters on heap
Text = new char[trueLength];

// Copy all characters from source to Text; +1 accounts for NULL-terminator
for ( int i = 0; i < trueLength; i++ )
    Text[i] = text[i];

return *this;
}

***bool& String::operator ==(string cmp2)***
{
};

Answer 1

你的compareTo声明有const，而定义没有const，这意味着它们的定义有不同的签名和声明：

bool& compareTo(const String& cmp1);
                ^^^
bool& String::compareTo(string cmp2)
{
};

是的，为什么你的compareTo会返回bool&？

还应该避免任何头文件中的using namespace std;。见why-is-using-namespace-std-considered-a-bad-practice-in-c

声明是不兼容的，初学c ++

1 个答案: