Question

头文件：

#ifndef CONTMEM_H
#define CONTMEM_H

class Contmem {
public:
    Contmem(int a, int b, int c);

    int total;
    int mem;
    const int constmem;
    int printconst() const;
    const int constant;
    void print();
};

#endif // CONTMEM_H

Contmem.cpp文件：

#include "Contmem.h"
#include <iostream> 

Contmem::Contmem(int a, int b, int c)
    : mem(a), constmem(b), constant(c)
{
    total = mem * constmem * constant;
}

void Contmem::print()
{
    std::cout << "This is my variable member " << mem << " and this is my constmem member " << constmem << "with the constant member" << constant << std::endl;  
}

int  Contmem::printconst() const
{
    return total;
    std::cout << "This is the total variable " << total << std::endl;
}

主要功能：

#include <iostream>
#include "Contmem.h"

int main()
{
    Contmem cont(3, 4, 5);
    cont.print();
    const Contmem obj;
    obj.printconst();
}

错误文件：

|=== Build: Debug in CONST_&_MEMBER_INITIALIZER

 (compiler: GNU GCC Compiler) ===| C:\C++

CODEBLOCK\CONST_&_MEMBER_INITIALIZER\main.cpp||

In function 'int  main()':| C:\C++

 CODEBLOCK\CONST_&_MEMBER_INITIALIZER\main.cpp|9|error: 

 no matching function for call to 'Contmem::Contmem()'| 

C:\C++  CODEBLOCK\CONST_&_MEMBER_INITIALIZER\Contmem.h|8|note: candidate:

 Contmem::Contmem(int, int, int)| C:\C++

 CODEBLOCK\CONST_&_MEMBER_INITIALIZER\Contmem.h|8|note:   candidate

 expects 3 arguments, 0 provided| C:\C++

 CODEBLOCK\CONST_&_MEMBER_INITIALIZER\Contmem.h|5|note: candidate:

 Contmem::Contmem(const Contmem&)| C:\C++

 CODEBLOCK\CONST_&_MEMBER_INITIALIZER\Contmem.h|5|note:   candidate

 expects 1 argument, 0 provided| ||=== Build failed: 1 error(s), 0

 warning(s) (0 minute(s), 0 second(s)) ===|

Answer 1

您缺少类的默认构造函数。你只有这个

Contmem::Contmem(int a, int b, int c)
    : mem(a), constmem(b), constant(c)
{
    total = mem * constmem * constant;
}

但是这里

int main()
{
    Contmem cont(3, 4, 5);
    cont.print();
    const Contmem obj; // <--here
    obj.printconst();
}

你试图构造一个新的Contmem对象而不传递这3个参数

实际上，那些编译器错误告诉你真正的问题是什么。

Answer 2

prepare(for segue: UIStoryboardSegue, sender: Any?)

尝试调用默认构造函数const Contmem obj;。

但因为：

Contmem()

有一个mem-initializer和一个Contmem::Contmem(int a, int b, int c) : mem(a), constmem(b), constant(c)成员，你的默认构造函数是 deleted。

因此，编译器无法将该语句与任何现有构造函数匹配，因为只存在mem-initializer构造函数。

当我用main中的const对象调用const函数时，继续出错

2 个答案: