C - Creating Sub Function To realloc Array Size

Question

I'm having an issue with pointers. I've read through 30+ posts on this subject and none match my setup. Here's what I'm trying to do:

void doSomething(myStruct **myList)
{
    resizeMyList(myList,5);

    myList[0] = '42';
    myList[1] = '43'; // ERRORS OUT OF MEMORY
}

void resizeMyList(myStruct **theArray,int size)
{
    myStruct *new_ptr = realloc(*theArray,(size * sizeof myStruct));

    if(new_ptr)
         *theArray = new_ptr;
    else
         printf("died");
}

After my resize function executes myList fails to get the new pointer. What am I doing wrong?

could you add more details? do you get new_ptr=NULL? and what's with the comment ERRORS OUT OF MEMORY? — H_squared
– H_squared, Commented Nov 14, 2013 at 9:52
sizeof myStruct is not your real code, that won't compile. It should be sizeof *new_ptr. — unwind
– unwind, Commented Nov 14, 2013 at 9:56

Some programmer dude · Accepted Answer · 2013-11-14 09:52:37Z

3

You do

myList[0] = ...

but myList is a double pointer so it should be

(*myList)[0] = ...

Also, you try to assign multi-character literals to a structure.

answered Nov 14, 2013 at 9:52

Some programmer dude

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2 Comments

Mark Löwe Over a year ago

Wow, parens?? I was actually doing the *myList, and forgot to put it in my sample code. After adding it, it worked. Amazing how the littlest things make all the difference. Thank you!

Some programmer dude Over a year ago

@MarkLöwe It's due to the operator precedence rules, array subscripting has higher precedence than pointer dereference.

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