c++中的toString()方法

toString() method in C++?

本文关键字：方法 toString 中的 c++      更新时间：2023-10-16

不知道我做错了什么，但我的代码是这样的:

std::wstring MediaDescription::toString()
{
    std::wstring theFile = std::wstring(L""fileName":"") + mFilename + std::wstring(L""");
    std::wstring theAuthor = std::wstring(L""author":"") + mAuthor + std::wstring(L""");
    std::wstring theAlbum = std::wstring(L""album":"") + mAlbum + std::wstring(L""");
    std::wstring theGenre = std::wstring(L""genre":"") + mGenre + std::wstring(L""");
    std::wstring theType = std::wstring(L""mediaType":") + mMediaType;
    std::wstring theTitle = std::wstring(L""title":"") + mTitle + std::wstring(L""");
    return std::wstring(L"{") + theFile + std::wstring(L",") + theAuthor + std::wstring(L",") + theAlbum + std::wstring(L",") + theGenre + std::wstring(L",") + theType + std::wstring(L",") + theTitle +     std::wstring(L"}");
}
我得到的错误是: 
 class:"MediaDescription" has no member of "toString"

但我不明白如何正确修改语法或我错过了什么。这是尝试将toString从Java语法转换为c++语法。

我的头文件如下:

#pragma once
#include <iostream>
#include <memory>
#include <string>
class MediaDescription : public std::enable_shared_from_this<MediaDescription>
{
/// <summary>
/// A media type of either Music or Video.
/// </summary>
private:
const std::wstring mMediaType;
/// <summary>
/// A title of a song or a video/movie.
/// </summary>
const std::wstring mTitle;
/// <summary>
/// A name for the author/actor/actress of the media.
/// </summary>
const std::wstring mAuthor;
/// <summary>
/// A name for the album of the song.
/// </summary>
const std::wstring mAlbum;
/// <summary>
/// A genre of the video.
/// </summary>
const std::wstring mGenre;
/// <summary>
/// A filename of the media
/// </summary>
const std::wstring mFilename;
public:
MediaDescription();
/// <summary>
/// MediaDescription constructor. </summary>
/// <param name="mediaType"> a media type of music or video </param>
/// <param name="title"> the title of the media </param>
/// <param name="author"> the author of the media </param>
/// <param name="album"> the album only applying to music </param>
/// <param name="genre"> the genre of the media </param>
/// <param name="filename"> the filename of the media </param>
MediaDescription(const std::wstring &mediaType, const std::wstring &title, const std::wstring &author, const std::wstring &album, const std::wstring &genre, const std::wstring &filename);
/// <summary>
/// Returns a media type of either music or video. </summary>
/// <returns> a media type. </returns>
virtual std::wstring getMediaType();
/// <summary>
/// Returns a title of a song or video/movie.
/// </summary>
/// <returns> a title of the media. </returns>
virtual std::wstring getTitle();
/// <summary>
/// Returns a name for the author of the media or leading actor/actress of video.
/// </summary>
/// <returns> a name of the author/actor/actress </returns>
virtual std::wstring getAuthor();
/// <summary>
/// Returns a name for the album of the song.
/// </summary>
/// <returns> a name of the album. </returns>
virtual std::wstring getAlbum();   
/// <summary>
/// Returns a genre of the video/movie.
/// </summary>
/// <returns> a genre of the video. </returns>
virtual std::wstring getGenre();
/// <summary>
/// Returns a filename of the media file.
/// </summary>
/// <returns> a filename of the media. </returns>
virtual std::wstring getFilename();
};

如果我这样做:

virtual std::wstring toString() override;

则得到以下错误:

'MediaDescription::toString': method with override specifier 'override' did not override any base class methods

您可能应该这样修改名为MediaDescription的类:

class MediaDescription {
/*code*/
public: /*or anything you need*/
    /*code*/
    std::wstring toString();
}

如果在子类的虚函数上指定了override c++ 11关键字，则其父类必须具有相同的虚函数签名。

生活例子

#include <iostream>
using namespace std;
struct Parent
{
    virtual void DoWork1() {}
    void DoWork2() {}
};
struct Child : Parent
{
    void DoWork1() override {} // OK !
    void DoWork1(int) override {} // error !
    void DoWork2() override {} // error !
};
int main()
{
}

另一个选项是添加覆盖std::to_string:

#include <string>
std::string std::to_string(MediaDescription &value) {
    // convert to string ...
}

这也是一个选项

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