程序崩溃从C函数访问动态分配的数组

Question

thanks for taking the time to read this. I'm having my program crash as soon as i try to access an array which was previously dynamycally allocated in a function. Here's some code

//function to allocate my array, gives an array as return
Player* allocate(Player **a, int n) { 
    *a = (Player *) malloc(sizeof(Player)*(n));
    return *a;
}

//populating my allocated array, return an array
Player* initializePlayers(Player *a, int n){
    int i=0;
    char tmp[MAXCHAR];
    for(i=0; i<n; i++){
        printf("Insert player name %d\n", i);
        scanf("%s", tmp);
        strcpy(a[i].playerName,tmp);
        printf("Player %s assigned.\n", a[i].playerName);
        a[i].playerNumber=i;
    }
return a;
}

//setup function which includes both the above ones, called from main
void setup(Player *array, int *nPlayers){
    int done=0;
    while (done==0){
    printf("How many players?\n");
    scanf("%d", nPlayers);
    if (*nPlayers <2 || *nPlayers>8){
        printf("Choose between 2 and 8\n");
            waitFor(2);
            clear();
            done=0;
       }
    else done=1;
    }
    allocate(&array, *nPlayers);
    initializePlayers(array, *nPlayers);
}

from my main

    Player * array=NULL;
    //I'm passing nPlayers because i want the value to be saved and available on my main
    setup(array, &nPlayers); 

    for (i=0; i<nPlayers; i++){
        printf("It's %s 's turn\n", (array)[i].playerName);
        dices=diceRoll(&same);
    }

I'm fairly new to programming so I might be missing something that is actually pretty obvious, please don't take anything for granted

Answer 1

Modification to the copied argument array in the function setup() won't affect local variables in function main() . Dereferencing NULL will invoke undefined behavior and your program just happened to crash .

Your setup() should be like this:

void setup(Player **array, int *nPlayers){

    /* ... */

    allocate(array, *nPlayers);
    initializePlayers(*array, *nPlayers);
}

and it should be called like this:

Player * array=NULL;
//I'm passing nPlayers because i want the value to be saved and available on my main
setup(&array, &nPlayers);