C++ Errors in constructors

Question

I've got a problem with my code. I've got a class called Player which looks like this

class Player
{
public:
   ...
Player();
Player(string firstName, string lastName, int birthYear);
~Player();
   ...
};

My source.cpp looks like this

string firstName = ...;
string lastName = ...;
int birth = ...

Player team[x](firstName, lastName, birth); // <--- This is were I get my errors

My errors are saying

error C3074: an array can only be initialized with an initializer-list

error C2466: cannot allocate an array of constant size 0

error C2057: expected constant expression

The constructor I want to use is Player(string firstName, string lastName, int birthYear). I think that I might be using the default constructor in source.cpp

I want to create 5x Player team[x](firstName, lastName, birth)

But this is where I get my errors. Any suggestions?

Please post your code here. Which of those errors is confusing you? — Ed Swangren
– Ed Swangren, Commented Feb 14, 2014 at 21:01
I tried to. But when I use the code function on this page, and then copy my code, it just puts a code snippet around 1 line. I don't fancy copying all of my lines. Is there a better way to copy code to this page? — Krippkrupp
– Krippkrupp, Commented Feb 14, 2014 at 21:02
@user3194111 select code, copy, come here, paste, adjust indent. Look at the help options for information about formatting. — crashmstr
– crashmstr, Commented Feb 14, 2014 at 21:03

Ed Swangren · Accepted Answer · 2014-02-14 21:46:37Z

3

This line simply isn't valid:

Player team[x](firstName, lastName, birth); // <--- This is were I get my errors

It doesn't make sense. You're trying to declare an array and call a constructor at the same time. You already created your team array. If you want to create a Player and assign it then you would use:

team[x] = Player(firstName, lastName, birth);

Of course, you already created a bunch of them (default initialized) when you created the array in the first place. Since this is C++, use a std::vector<Player>.

Also, something that is wrong but is not generating an error:

int matches;
int* dates = new int[matches];

Here, matches is uninitialized and its value is indeterminate. Reading that variable invokes undefined behavior, and certainly you don't want any random size for your array (why aren't you using a vector again?) You need to initialize matches before using it.

edited Feb 14, 2014 at 21:46

answered Feb 14, 2014 at 21:04

Ed Swangren

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1 Comment

Krippkrupp Over a year ago

Thanks. I've never used vectors, that's why. I'll google around and look for it. Thanks

Anachronous · Accepted Answer · 2014-02-14 21:43:48Z

0

One problem with your code is that the variable matches hasn't been initialized and has an indeterminate value.

int matches;
int* dates = new int[matches];

You should initialize matches before calling new int[matches].

A team of nrOfPlayers players is constructed when you allocated an array of Players:

Player* team = new Player[nrOfPlayers];

You can now fill in a player's information by creating a temporary Player object and assigning it to an element in team. This will call Player's implicitly defined copy assignment operator:

Replace line 75 with:

team[x] = Player(firstName, lastName, birth); // copy constructor is called

edited Feb 14, 2014 at 21:43

answered Feb 14, 2014 at 21:25

Anachronous

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4 Comments

Ed Swangren Over a year ago

"This is happening because you're trying to allocate an array of integers with the variable matches which hasn't been defined." - That's not true. matches is uninitialized and has an indeterminate value, and reading it is UB, but that is not a compiler error. The size error comes from this line- Player team[x](firstName, lastName, birth);

Anachronous Over a year ago

@EdS. Thanks for pointing that out. I revised my entry to reflect your correction.

Krippkrupp Over a year ago

Okay. The player constructor works now. The problem now is - as you mentioned - the int dates[matches]. My idea was to put int* dates = new int[matches] the line below sas >> matches; However, that did not work. I got some linking errors

Ed Swangren Over a year ago

@user3194111: What is the type of sas?

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