How Does C Allocate Memory for Vectors: Stack or Heap?

Memory Allocation of Vectors in C

When working with vectors in C , it's essential to understand their memory allocation characteristics. Consider the following statements:

• vector vect;
• vector *vect = new vector;
• vector vect;

Stack or Heap Allocation?

• vector vect: This allocates the vector header on the stack while the actual elements are allocated on the heap (free store).
• vector *vect = new vector;: Everything, including the vector pointer and elements, is allocated on the heap.
• vector vect: The vector is allocated on the stack, but the pointers within it are allocated on the heap. The targets of these pointers can vary based on usage.

Internal Memory Allocation

For vectors and other STL containers, memory allocation occurs as follows:

• The container header, which stores metadata such as size and capacity, is usually allocated on the stack.
• The actual elements are allocated dynamically on the free store.
• For vectors of pointers, the pointers themselves are also allocated on the free store, while the objects they point to can have varying memory allocation mechanisms.

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