CODEWITHSUNDEEP
arrayscvoid-pointers
Jacob S
Jacob S

Reputation: 1

Accessing the array size in front of void array

Im trying to store the size of an array of an arbitrary type in front of the array so that the size can be accessed through the -1st element of the array. The goal of my function is to increment the array back by the size of an int pointer (where the size should be stored) and return that to the calling function.

The issue i'm having is that when the array is of type int, the incrementation isnt happening correctly and is returning the wrong value. However, when the array is of type double, it works perfectly. Here is the code for the function:

int getSizeArray(void * array)
{
     return *((int*)(array - 1));
}

Upvotes: 0

Views: 547

Answers (1)

Armali
Armali

Reputation: 19375

We can't sensibly perform arithmetic with a void pointer (array - 1); rather cast array to the actual type first:

return ((int *)array)[-1];

Of course it is assumed that array as well as this size element is initialized correctly.

Upvotes: 2

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