Is it on the Stack or Heap?

c, heap-memory, stack-memory

Solution

Leaving global variables and variables declared with `static` modifier (which are allocated in a separate memory region) aside, local variables declared in a function body are allocated on the stack whereas whatever you call `malloc` for is allocated on the heap. Also, C99 variable sized arrays and memory allocated with `_alloca` will end up on stack.

int* x[10];   // The addresses are held on the stack
int i;        // On the stack
for(i = 0; i < 10; ++i)
   x[i] = malloc(sizeof(int)*10);  // Allocates memory on the heap

For example, in the above code, there's an array of `int*` values on the stack holding addresses to 10 different locations in the heap.

Problem

I have some C code that is something of a puzzle. For a reason to do with this code, I'm wondering how I can tell if a `struct` object is ending up on the heap or stack? The objects are not being created with `malloc` or `calloc`. They start their life in the form of an array. For the purposes of this post, I'm going to call the struct Emp. ``` Emp myEmp[6]; /* Each myEmp[?] item is populated in code */ ``` The objects are sorted and manipulated in various ways and at some point, the objects are copied and then handed to a array-pointer. The copy is done via `memcpy`. The objects are then put in to something like: `Emp* emps_a[6]`. The objects go from a copy and are assigned in to the above emps_a. ``` int i; for( i = 0; i < n; i++ ) { emps_a[i] = myEmpsCopy + i; } ``` I'm not sure if some or any of this has bearing on my question. I never need free() or do memory clean up... I'm afraid I don't know too much about C. The help is greatly appreciated.

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