note: 'person::person()' is implicitly deleted because the default definition would be ill-formed

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; } 

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\dxs\Documents\C++\Challenges\DataStructures\DataStructures.cpp -o obj\Debug\DataStructures.o C:\Users\dxs\Documents\C++\Challenges\DataStructures\DataStructures.cpp: In function 'int main()': C:\Users\dxs\Documents\C++\Challenges\DataStructures\DataStructures.cpp:32:12: error: use of deleted function 'person::person()' C:\Users\dxs\Documents\C++\Challenges\DataStructures\DataStructures.cpp:23:8: note: 'person::person()' is implicitly deleted because the default definition would be ill-formed: C:\Users\dxs\Documents\C++\Challenges\DataStructures\DataStructures.cpp:23:8: error: uninitialized non-static const member 'const int person::numberOfAddresses' C:\Users\dxs\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)) 

I can't find anything with Google relating to my problem. Any ideas? I'm using Code::Blocks with g++.

2 Answers

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.

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; ... 

Alternatively, you can simply write your own default constructor for the class.

The problem has not to do with the default-constructor. There is a constant in the class declaration but the default (no argument) constructor does not guarantee that the constant will be defined. Suggest using an "initializer list".

struct Person { int id; string name; date birthdate; const int numberOfAddresses; address addresses [1]; Person(int); // constructor declaration Person() : numberOfAddresses(1) {} // constructor definition. // ": numberOfAddresses(1)" is the initializer list // ": numberOfAddresses(1) {}" is the function body }; Person::Person(int x) : numberOfAddresses(x) {} // constructor definition. ": numberOfAddresses{x}" is the initializer list int main() { Person Bob; // calls Person::Person() Person Shurunkle(10); // calls Person::Person(int) }