Initialize array of structs - c code error

Question

I have a struc called player, and I need to make an array of MAX players, so I based on the following page C - initialize array of structs, like so:

DEFINE MAX 200

typedef struct
{
   int ID;
} Player;

Player* PlayerList = malloc(MAX * sizeof(Player));

Problem is I keep getting the following error

error: expected expression before ‘=’ token
error: initializer element is not constant

Base code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX = 200;

typedef struct
{
    int ID;
} Player;

Player *PlayerList;

int start()
{
    PlayerList = malloc(MAX * sizeof(Player));
    return 1;
}

int main(int argc, char const *argv[])
{
    /* code */
    return 0;
}

is PlayerList a defined type, which you're also trying to use as a variable? What is MAX defined as? — sapi
– sapi, Commented May 2, 2013 at 0:09
Please post short but complete examples - other people should be able to paste your code listing to a file and compile it without changes (or fail to compile, but with exactly the same errors). — Staven
– Staven, Commented May 2, 2013 at 0:13

This isn't my real name · Accepted Answer · 2013-05-02 00:12:01Z

2

You can't call malloc() from outside of any function. Just declare Player* PlayerList;, and let one of the first things you do in main() be PlayerList = malloc(MAX * sizeof(Player));.

answered May 2, 2013 at 0:12

This isn't my real name

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8 Comments

Morki Over a year ago

I see. But I need PlayerList to be a global, how would do that.

This isn't my real name Over a year ago

You can declare PlayerList outside of any function, but using a function call (malloc()) to initialize it, that can only be done in a context where function calls are valid.

This isn't my real name Over a year ago

You need to show your full code, then. complete, compilable, minimal code sample.

This isn't my real name Over a year ago

And there's the difference! #define MAX = 200; is not the same as #define MAX 200. remember, #define is a token substitution performed by a preprocessor. By the time the compiler tries to actually compile your code, you're now left with PlayerList = malloc(= 200; * sizeof(Player));, which I'm sure you'll agree is nonsensical.

This isn't my real name Over a year ago

Can't do that. You can only free() exactly the things you get from malloc(). You could set PlayerList[2] to some flag value indicating that it's invalid, or you could switch to an entirely different model, and use a linked link to keep your players in.

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BLUEPIXY · Accepted Answer · 2013-05-02 00:29:28Z

1

You can not use only constant for initialization in old type 'C'.

rewrite

Player* PlayerList = malloc(MAX * sizeof(Player));

to

Player* PlayerList;
PlayerList = malloc(MAX * sizeof(Player));

Add E.G.:

#include <stdlib.h>

#define MAX 200

typedef struct
{
   int ID;
} Player;

Player* PlayerList=NULL;

int main(void){
    PlayerList = malloc(MAX * sizeof(Player));
    return 0;
}

edited May 2, 2013 at 0:29

answered May 2, 2013 at 0:11

BLUEPIXY

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10 Comments

Morki Over a year ago

Can I make this global some how?

BLUEPIXY Over a year ago

@Morki note: You could not write executable statements outside a function.

Morki Over a year ago

Can I do something like static PlayerList = malloc(MAX * sizeof(Player));

This isn't my real name Over a year ago

inside a function, yes. But it's not the same thing.

BLUEPIXY Over a year ago

@Morki I think that you cannot even static, but do not you mean C++? 　It is possible if C++ is an explicit cast is required in that case.

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