how free of memory happen in this case???

Question

#include <stdio.h>
void func(int arr[],int xNumOfElem)
{
    int j;
    for(j=0; j<xNumOfElem; j++)
    {
       arr[j] = j + arr[j];
       printf("%d\t",arr[j]);
    }
    printf("\n");
}

int main()
{

    int *a,k;
    a = (int*) malloc(sizeof(int)*10);


    for(k = 0; k<10; k++)
    {
        a[k] = k;
        printf("%d\t",a[k]);
    }
    printf("\n");

    func(a,10); //Func call

    free(a);                                                                                                                              
}

Inside the the function "func" who will allocate/deallocate memory for dynamic array "arr".

arr is an function argument.

Answer 1

One need not allocate memory for array arr in the function fun. The memory for array is allocated in the main function before the fun is called. Also main is deallocating the memory once it is done using the memory; so fun need not do deallocating as well.

Answer 2

Think of it this way:

void func(int arr[],int xNumOfElem)
{
    int j;
    for(j=0; j<xNumOfElem; j++)
    {
       arr[j] = j + arr[j];
       printf("%d\t",arr[j]);
    }
    printf("\n");
}

is equivalent to:

void func(int *arr /* look here */,int xNumOfElem)
{
    int j;
    for(j=0; j<xNumOfElem; j++)
    {
       arr[j] = j + arr[j];
       printf("%d\t",arr[j]);
    }
    printf("\n");
}

Answer 3

You don't pass an array, you only pass the pointer to an int. The line

void func(int arr[],int xNumOfElem)

is just an other way to write

void func(int* arr,int xNumOfElem)

the compiler itself can't allocate memory for a copy of a, as the size of a is dynamic and therefor unknown to the compiler. print the values of a after the call to func to see that a has changed.

To get a copy change your func method to:

void func(int const* const b,int xNumOfElem)
{
    int* arr = malloc(sizeof(int)*xNumOfElem);
    memcpy(b,arr,xNumOfElem);
    int j;
    for(j=0; j<xNumOfElem; j++)
    {
       arr[j] = j + arr[j];
       printf("%d\t",arr[j]);
    }
    printf("\n");
    free(arr);
}