Memory Management

Question 1

What are the four areas of memory?

Answer 1

Code segment, data segment, function call stack, heap

Question 2

What does the code segment contain?

Answer 2

Program instructions, addresses of functions

Question 3

What does the data segment contain?

Answer 3

Global variables, static variables, literals

Question 4

What is the function call stack used for?

Answer 4

Managing the order of function calls, storing local variables (including parameters)

Question 5

What is the heap?

Answer 5

Part of the data segment, it stores all dynamically allocated memory

Question 6

What is a stack?

Answer 6

A data structure analogous to a stack of dishes. Data is pushed in and popped out in a last-in, first-out fashion.

Question 7

What is the function call stack?

Answer 7

It manages the function-call-and-return mechanism

Question 8

What does the function call stack contain?

Answer 8

Automatic variables, return address of the next instruction in the calling function

Question 9

What is control flow?

Answer 9

The order in which instructions are executed

Question 10

How does control flow work?

Answer 10

Begin at first instruction in main() function, continue sequentially to next instruction, when a function is called, control transfers to the first instruction of that function, and when returned, control is transferred back to the calling function

Question 11

How does the function-call-and-return mechanism work?

Answer 11

When a function is called, a new stack frame is created and pushed onto the function call stack. The top frame always belongs to the function currently executing. When a called function returns, its stack frame is popped off, memory from local variables freed up, and control transferred back to the calling function.

Question 12

What does a stack frame contain?

Answer 12

Automatic variables (parameters and locals), and the address of the next instruction in the calling function, where control will be transferred after the called function ends.

Question 13

What is the heap?

Answer 13

A portion of program memory used for dynamically allocated memory

Question 14

What is static allocation?

Answer 14

Memory allocation that happens at compile-time. Memory is allocated statically simply by declaring variables.

Question 15

What is dynamic allocation?

Answer 15

Memory allocation that happens at run-time. In C we do it by using the malloc() library function

Question 16

What is a common problem with dynamically allocated memory?

Answer 16

Memory leaks

Question 17

What is a memory leak?

Answer 17

Block of dynamically allocated memory that is never deallocated, which can eventually cause a crash. Done using free() function

Question 18

What is memory allocation?

Answer 18

Reserving bytes in memory