Lecture 7: Structures

Question 1

A good location to leave structures is…

Answer 1

at the top of your files (or in header files).

Question 2

Defining a structure

Answer 2

tells the compiler about the new type, but doesn’t allocate storage.

Question 3

Declaring a variable

Answer 3

tells the compiler the type and identifier (name) you chose.

Question 4

What happens when you pass a structure to a function?

Answer 4

It is passed by value.

Question 5

Ways to assign values to struct

Answer 5

struct example name = { a, b, c }; // Bad practice. Don’t.
struct example name = { .x = a, .y = b, .z = c } // Much better.
struct example name = { .x = a }; // y and z uninitialized.

Question 6

Compound literals.

Answer 6

name = (struct example) { .x = a, .y = b, .z = c };
This is used to assign a value to something already declared. Or, you can just set piece by piece.

Question 7

Arrays of structs

Answer 7

struct example[] = { {.x = a}, {.x = b} };
struct example[] = { [0].x = a, [1].x=b }

Question 8

Can structs contain other structs?

Answer 8

Yes.

Question 9

Can you define a structure without a name?

Answer 9

You could. But it’s not recommended.
I.e.
struct
{
// stuff goes here
} arr_of_these[n];

Question 10

go back to slides and find information about memory. the stack. etc

Question 11

What operations are allowed for the stack?

Answer 11

“push” and “pop”. Add an element to the top, or remove it.

Question 12

What happens to memory when a function is called?

Answer 12

An entry is pushed onto the stack, containing arguments, space for variables in the function, and a return address.

Stack grows when a function is called and shrinks as it returns. It grows from wherever it is.

Note: in gdb, bt will show the contents of the stack. Alternatively, bt –full

Question 13

notes on processes