注意:'person :: person()'被隐式删除,因为默认定义格式不正确 [英] note: 'person::person()' is implicitly deleted because the default definition would be ill-formed
问题描述
我正在研究一个示例程序,以帮助我学习C ++中的结构。这是我的代码:
I'm working on an example program to help me learn structs in C++. Here's my code:
#include <stdio.h>
#include <iostream>
#include <string>
using namespace std;
int nextPersonID = 0;
int nextAddressID = 0;
struct date {
int day;
int month;
int year;
};
struct address {
int id;
string address;
date effectiveDate;
date expirationDate;
};
struct person {
int id;
string name;
date birthdate;
const int numberOfAddresses;
address addresses [1];
};
int main () {
person bob;
bob.name = "Bob";
bob.id = nextPersonID;
nextPersonID++;
bob.birthdate.day = 1;
bob.birthdate.month = 1;
bob.birthdate.year = 1990;
bob.numberOfAddresses = 1;
bob.addresses[0].address = "31415 E. Pi Blvd.";
bob.addresses[0].id = nextAddressID;
nextAddressID++;
bob.addresses[0].effectiveDate.day = 1;
bob.addresses[0].effectiveDate.month = 1;
bob.addresses[0].effectiveDate.year = 1990;
bob.addresses[0].expirationDate.day = 1;
bob.addresses[0].expirationDate.day = 1;
bob.addresses[0].expirationDate.day = 2020;
cout << bob.name;
}
但是当我尝试编译时,它失败并显示注意:'person :: person()'被隐式删除,因为默认定义格式不正确。
。这是我的构建日志:
But when I try to compile, it fails with note: 'person::person()' is implicitly deleted because the default definition would be ill-formed.
. Here's my build log:
-------------- Build: Debug in DataStructures (compiler: GNU GCC Compiler)---------------
mingw32-g++.exe -Wall -g -std=c++11 -I"C:\Program Files (x86)\CodeBlocks\MinGW_Dev_Libs\include\SDL2" -c C:\Users\Duncan\Documents\C++\Challenges\DataStructures\DataStructures.cpp -o obj\Debug\DataStructures.o
C:\Users\Duncan\Documents\C++\Challenges\DataStructures\DataStructures.cpp: In function 'int main()':
C:\Users\Duncan\Documents\C++\Challenges\DataStructures\DataStructures.cpp:32:12: error: use of deleted function 'person::person()'
C:\Users\Duncan\Documents\C++\Challenges\DataStructures\DataStructures.cpp:23:8: note: 'person::person()' is implicitly deleted because the default definition would be ill-formed:
C:\Users\Duncan\Documents\C++\Challenges\DataStructures\DataStructures.cpp:23:8: error: uninitialized non-static const member 'const int person::numberOfAddresses'
C:\Users\Duncan\Documents\C++\Challenges\DataStructures\DataStructures.cpp:39:29: error: assignment of read-only member 'person::numberOfAddresses'
Process terminated with status 1 (0 minute(s), 1 second(s))
3 error(s), 0 warning(s) (0 minute(s), 1 second(s))
我在Google找不到与我的问题有关的任何东西。有任何想法吗?
我在g ++中使用Code :: Blocks。
I can't find anything with Google relating to my problem. Any ideas? I'm using Code::Blocks with g++.
推荐答案
好吧,问题不在于该注释 。 注释仅说明错误的原因。错误是,当类 person
没有默认构造函数时,您试图默认构造 person
对象。
Well, the problem is not with that "note". The "note" simply explains the reason for the error. The error is that you are trying to default-construct your person
object when class person
does not have a default constructor.
您可以 {}
-初始化该const成员,而不是尝试默认构造它,代码将编译
Instead of trying to default-construct it, you can {}
- initialize that const member and the code will compile
person bob = { nextPersonID++, "Bob", {}, 1 };
bob.birthdate.day = 1;
bob.birthdate.month = 1;
bob.birthdate.year = 1990;
...
或者,您可以简单地为该类编写自己的默认构造函数。
Alternatively, you can simply write your own default constructor for the class.
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