无效使用非静态数据成员

时间:2013-05-04 16:48:30

标签: c++

我想创建一个文件,在其中我可以将Person添加到PersonList,包括一个计数器,确保不超过PersonList的容量。我评论了所有功能,以明确他们应该执行的任务。

在编译期间,我收到以下错误:

invalid use of non-static data member 'PersonList::m_Capacity'

不幸的是我无法弄清楚代码中的错误:

的main.cpp

#include <iostream>
#include "Person.h"
#include "PersonList.h"

int main()
{

    Person p1 = Person("John", 21);
    Person p2 = Person("Elham", 19);
    PersonList p_list = PersonList();

    p_list.add(p1);
    p_list.add(p2);

    std::cout << p_list.get_Size() << std::endl;
    Person p = p_list.get(0);
    std::cout << p.get_Name() << " " << p.get_Age() << std::endl;

    return 0;
}

Person.h

#ifndef PERSON_H
#define PERSON_H

class Person
{
    public:
        Person();
        Person(std::string Name, int Age);

        void set_Name(std::string name);
        void set_Age(int age);
        std::string get_Name();
        int get_Age();

    private:
        std::string m_Name;
        int m_Age;
};

#endif // PERSON_H

Person.cpp

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

Person::Person(){}

Person::Person(std::string Name, int Age){
// pre:  0 <= Age
// post: m_Name, if pre Name (is true) Age = m_Age,
//       otherwise age = -1

    set_Name(Name);

    if (0 <= Age){

        set_Age(Age);
    }

    else{

        set_Age(-1);
    }

}

void Person::set_Name(std::string Name){
// post: m_Name = Name

    m_Name = Name;
}

void Person::set_Age(int Age){
// pre:  0 <= Age
// post: if pre Age (is true) = m_Age, otherwise m_Age = -1;

    if (0 <= Age){

        m_Age = Age;
    }

    else set_Age(-1);
}

std::string Person::get_Name(){
// post: returns name

    return m_Name;
}

int Person::get_Age(){
// post: returns age

    return m_Age;
}

PersonList.h

#ifndef PERSONLIST_H
#define PERSONLIST_H

class PersonList
{
    public:
        PersonList();

        void add(Person p);
        void set_Size(int Size);
        int get(int index);
        int get_Size();

    private:
        const int m_Capacity;
        const Person m_Empty;
        Person m_Data[m_Capacity];
        int m_Size;

};

#endif // PERSONLIST_H

PersonList.cpp

#include "Person.h"
#include "PersonList.h"

PersonList::PersonList()
m_Capacity(10), m_Empty(Person())
{
// post: has created a new PersonList-object with
//      CAPACITY elements and size = 0

    set_Size(0);
}

void PersonList::add(Person p){
// pre:  size < CAPACITY
// post: if pre (is true) p has been stored at the
//      first empty location. size was incremented.

    if (m_Size < m_Capacity){

        m_Data[m_Size] = p;
        set_Size(m_Size+1);
    }

}

void set_Size(int Size){

    m_Size = Size;
}

int PersonList::get(int index){
// pre:  0 <= index && index < size
// post: if pre returns data[index] otherwise returns EMPTY

    if (0 <= index && index < m_Size){

        return m_Data[index];
    }

    else{

        return m_EMPTY;
    }
}

int PersonList::get_Size(){
// post returns size;

    return m_Size;

}

2 个答案:

答案 0 :(得分:5)

C ++不支持变长数组(VLA),这就是您所拥有的:

Person m_Data[m_Capacity];

为此,m_Capacity必须是编译时常量。

除此之外,您的默认构造函数中存在语法错误,其中需要:来指示初始化列表:

PersonList::PersonList() : m_Capacity(10), m_Empty(Person()) { .... }
//                       ^ Here!

答案 1 :(得分:0)

构造函数和初始化列表必须用冒号分隔。喜欢这个

PersonList::PersonList() : m_Capacity(10), m_Empty(Person())