Week 4

Monday

Return Exam

Introduction to functions

examples of built in functions

sqrt & other math functions

void - verb names

non-void - noun names - must return a value

function signature (aka. declaration/definition) vs function call

arguments and parameters

parameter - part of the function's signature
argument - part of the function call

non-void functions can only return one value but can have multiple return statements

//function aka method, routine, sub-routine, sub

Why use functions?

documentation
modularization aka componentization aka hiding the mess
reuse - saves time and is more reliable

reduces complexity: Functions can simplify a program greatly and make it easier to understand what is happening, and program tend to be shorter

Examples

none

Assign Homework

Read Chapter 5 sections 1-10

Prime Factors C++ (Due Tuesday)

Tuesday

c++ return statement

by value vs. by reference

By Value:

By default, arguments are passed by value to a function which means a copy is made of the argument
Any changes made to a parameter are only changing the copy, not the actual argument
It's like handing someone a photocopy of a paper you wrote; any changes the person makes to the photocopy doesn't change the original paper

By Reference:

This means the parameter is just another name for the argument
Therefore any changes made to the reference parameter will also change the argument (modifying x will change a, and modifying y will change b)
It's like handing someone the original paper you wrote; any changes the person makes to the original will affect the original.
Uses an ampersand (&)

only variables can be passed to a function that receives arguments by reference (literals cannot be passed by ref)

Work examples from Schaum's book chapter 5

Examples

none

Assign Homework

Work problems 5.21, 5.22, 5.24 and 5.25 from Schaum's book. Use Boolean return values rather than integers for 5.21 and 5.22. (Due Wednesday)

Wednesday

Black Box Diagram - From the diagram you can only see what is input and what is output but not how it works inside.

order of functions - functions must be "declared" before they are used

function prototypes - "prophecy" that you will write a function later

allow you to organize function in any order you want
if you do not write the function you will get a "linker" error

Declaration vs Definition

declaration - introduces an identifier and describes it. This is what the compiler needs to know.
definition - instantiates/implements the identifier. This is what the linker needs to know.

Examples

none

Assign Homework

Fraction Calculator Lab (Due Thursday)

Thursday

Function Lab day

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Examples

none