Blockchain Developer Certification Practice

Which type of data is stored in the stack?

1. Persistent variables

2. Local variables of reference types

3. Local variables of value types

4. Global variables

The correct answer is: Local variables of value types

The stack is a specific area of memory that is used for storing local variables and method call information in programming. When a function is called, a new block is created in the stack, which contains all the local variables defined in that function. Local variables of value types, such as integers or structs, are stored in this stack area. Value types hold their data directly, which means the actual value is stored in the allocated space. When a function exits, the stack space used for those local variables is automatically freed, making it efficient for memory usage. Persistent variables and global variables, however, are not stored in the stack. Persistent variables, often found in scenarios like database storage or file systems, require a different form of memory allocation. Global variables are typically stored in a different memory area, commonly in the heap or a separate data segment, so they remain accessible throughout the program duration, unlike local variables which are short-lived and limited in scope. Local variables of reference types would be stored on the heap, with their references (or pointers) on the stack, contrasting with value types which are stored directly in the stack itself.