C: What will happen if free() use an invalid pointer to release the memory ?

Answer 1

I wrote the code and tested, it is crashing.
Code snapshot:

#include<stdio.h>
#include<stdlib.h>

int main()
{
   int *ptr = malloc(sizeof(int)*5);
   free(ptr+1);
   return 0;
}

Answer 2

int main()
{
int *ptr;
ptr = (int*)malloc(sizeof(int)*5); /* malloc returns void pointer you need to typecast */
free(ptr);
return 0;
}