Question

我开始学习C ++，类，对象，结构等等，但我遇到了一些问题。

#include <iostream>

using namespace std;

class Owner
{
    public:
        // Getters
        string GetName(){return info.name;}
        int GetAge(){return info.age;}
        short int GetGender(){return info.gender;}

        // Setters
        void SetName(string value){info.name = value;}
        void SetAge(int value){info.age = value;}
        void SetGender(short int value){info.gender = value;}
    private:
        struct info
        {
            string name;
            int age;
            short int gender;
        };
};

class Pet
{
    public:
        // Getters
        string GetName(){return info.name;}
        int GetAge(){return info.age;}
        short int GetGender(){return info.gender;}

        // Setters
        void SetName(string value){info.name = value;}
        void SetAge(int value){info.age = value;}
        void SetGender(short int value){info.gender = value;}
    private:
        struct info
        {
            string name;
            int age;
            short int gender;
        }
};


int main()
{

    // Creating object ...

    cout << "qq" << endl;



    return 0;
}

但是当我尝试编译它时我遇到了这些错误：

In member function 'std::string Owner::GetName()':|
main.cpp|9|error: expected primary-expression before '.' token|
In member function 'int Owner::GetAge()':|
main.cpp|10|error: expected primary-expression before '.' token|
In member function 'short int Owner::GetGender()':|
main.cpp|11|error: expected primary-expression before '.' token|
In member function 'void Owner::SetName(std::string)':|
main.cpp|14|error: expected unqualified-id before '.' token|
In member function 'void Owner::SetAge(int)':|
main.cpp|15|error: expected unqualified-id before '.' token|
In member function 'void Owner::SetGender(short int)':|
main.cpp|16|error: expected unqualified-id before '.' token|
main.cpp|45|error: expected unqualified-id before '}' token|
In member function 'std::string Pet::GetName()':|
main.cpp|30|error: expected primary-expression before '.' token|
In member function 'int Pet::GetAge()':|
main.cpp|31|error: expected primary-expression before '.' token|
In member function 'short int Pet::GetGender()':|
main.cpp|32|error: expected primary-expression before '.' token|
In member function 'void Pet::SetName(std::string)':|
main.cpp|35|error: expected unqualified-id before '.' token|
In member function 'void Pet::SetAge(int)':|
main.cpp|36|error: expected unqualified-id before '.' token|
In member function 'void Pet::SetGender(short int)':|
main.cpp|37|error: expected unqualified-id before '.' token|
||=== Build finished: 13 errors, 0 warnings ===|

为什么它会给我这么多错误？

我不知道为什么，因为很明显，例如，

 string GetName()
 {
     return info.name;
 }

从结构info.name

返回一个字符串

我正在使用CodeBlocks。

Answer 1

您将结构声明为类型（Owner.info）而不是成员（this->info）。你可能想要这个：

struct OwnerInfo
{
    string name;
    int age;
    short int gender;
};

class Owner {
    // stuff..
private:
    OwnerInfo info;
};

或者，更合理的版本就是将它们直接放在那里，而不是在无意义的struct内：

class Owner {
    // stuff..
private:
    string name;
    int age;
    short int gender;
};

Answer 2

您误解了struct关键字的语法，而且实际的成员变量必须在访问成员函数之前声明。因此，将类声明更改为

class Owner { private: struct { string name; int age; short int gender; } info; public: // Getters string GetName(){return info.name;} int GetAge(){return info.age;} short int GetGender(){return info.gender;} // Setters void SetName(string value){info.name = value;} void SetAge(int value){info.age = value;} void SetGender(short int value){info.gender = value;} };

Answer 3

宣言：

private:
    struct info
    {
        string name;
        int age;
        short int gender;
    };

...定义嵌套结构类型info的布局，非常类似于整个类的定义。但是，info现在是嵌套在所有者中的类型，而不是作为所有者成员的该类型的实例。相反，尝试命名struct Info，然后在Owner的私有部分声明Info info = new Info();。

Answer 4

你创建了一个结构，因此告诉你的编译器“info”是一个具有以下属性的类型...

您需要声明“info”类型的变量。

info personalInfo;

将其声明为类成员，您可以创建Get-er和Set-er。

string GetName(){return personalInfo.name;}

More Information

Answer 5

您应该创建一个struct info对象。你不能在不创建对象的情况下直接访问结构的字段。为什么你需要结构？试试这个

class Owner
{
    private:
            string name;
            int age;
            short int gender;

    public:
        // Getters
        string GetName(){return this->name;}
        int GetAge(){return this->age;}
        short int GetGender(){return this->gender;}

        // Setters
        void SetName(string value){this->name = value;}
        void SetAge(int value){this->age = value;}
        void SetGender(short int value){this->gender = value;}
};

C ++简单类

5 个答案: