Cant access data after realloc struct vector

Question

I'm using reallocto reduce the size of my vector. I want to loose the last position only. so, if I have 10 positions and I use realloc to allocate enough space for 9 * sizeof(my_struct) will the vector get truncated and keep the old data but the last position ? I thought it was right, but when I try to print the value after the realloc I get Segmentation Fault error. Here is my code:

    //Instanciate the vector
    my_struct *struc;
    my_struct *buffer;

    //Allocate space for 10 slots
    struc = (my_struct *) malloc(10 * sizeof(my_struct));

    //realloc for 9 slots
    buffer = (my_struct *) realloc(struc, 9 * sizeof(my_struct));        
    if(buffer != NULL){
       struc = buffer;
    }

now if I try to use printf to check the elements inside the vector, I get Segmentaition Fault

OBS: The Vector has been filled up with data BEFORE the realloc. I didnt post here because I think it's unnecessary... Imagine the vector already with data in this code.

Answer 1

Your data can be moved by realloc(). So if there is any pointer to the data, after the call, such pointers would become invalid.