8- programmer-defined functions, local and global variables, call-by-value

Question 1

Function

Answer 1

named group of statements carrying out a particular task
to carry out its task the function accepts arguments

Question 2

Predefined function

Answer 2

provided in libraries for the benefit of all programmers

Question 3

Programmer-defined function

Answer 3

written by programmer

Question 4

Caller

Answer 4

function that invokes another

Question 5

Callee

Answer 5

function that is being invoked

Question 6

Function definition

Answer 6

specifies instructions that the function executes
consists of head, body

Question 7

Function prototype

Answer 7

declares (quickly introduces) the function

Question 8

Expanded form

Answer 8

mentions parameter types and names: names are optional but sometimes desirable for clarity
int add1(int i);

Question 9

Abbreviated form

Answer 9

mentions only parameter types
int add1(int);

Question 10

Local variable

Answer 10

variable that is declared inside a function is local (to that function): it cannot be used outside of the function
the scope of such variable is from declaration till end of function
parameters are also local variables
local variables of two different functions are different even if they have the same name
variables declared in main() are local to main()

Question 11

Global constant

Answer 11

a constant declared outside any function definition
it can be used (its scope is) anywhere in the program from the place it is declared

Question 12

Global variable

Answer 12

variable declared outside any function definition
int errorcode = 0;
global variable scope is any function of the program from variable declaration down, functions can read and update global variable
using global variables introduces side effects to functions
what’s “side effect” gain?
makes program hard to understand: avoid!