Stack vs. Heap: Where Does a Globally Declared Data Structure in C Live?

Memory Allocation in C : Stack vs. Heap for Global Data Structures

When declaring a data structure globally in C , the question arises whether it consumes stack memory or heap memory. To fully comprehend this, it's essential to understand the different memory segments a process utilizes.

Typically, a process possesses five main memory areas:

1. Code (text segment): Contains the executable code.
2. Initialized data (data segment): Stores global and static variables initialized with values at compile-time.
3. Uninitialized data (bss segment): Holds global and static variables uninitialized at compile-time, initialized to zero at runtime.
4. Heap: Dynamically allocated memory acquired using operators like new and malloc.
5. Stack: Stores local variables, function parameters, and return addresses.

Returning to the original question, if a data structure is declared globally (not within a function), it will be allocated either in the data segment (initialized data) or the bss segment (uninitialized data), depending on whether it's initialized or not. These segments reside in static memory, which is typically managed by the operating system and not accessible to the program.

Therefore, globally declared data structures in C do not consume stack memory.

The above is the detailed content of Stack vs. Heap: Where Does a Globally Declared Data Structure in C Live?. For more information, please follow other related articles on the PHP Chinese website!