Decision Branching - if/then/else

Let’s talk about decision branching and more specifically about the if/then/else constructs. Decisions control the flow of your program.

Your key takeaways are:

Conditional control statements determine the flow of the program
if/then
if/else
if/else if/else
The combination of the conditionals must evaluate to true for the if or else if to be true

Study Notes

The basic structure of a if/then branching code block is:

if ( conditions ) then do something

The basic structure of a if/else branching code block is:

if ( conditions ) then do something else do this instead

These allows you to set the conditions. But, what if the conditions are not set? What else can you do?

If you need more than one control path:

if ( conditions ) then do something else if ( conditions ) then do that else do this instead

Review the if/then statements in C, PHP, Python, and JavaScript below. Do you notice the similarities?

	if ( weatherIsSunny && ! weatherIsRaining && ! isWorking ) {
	printf( "Going to the festival" );
	} else if ( movieIsPlaying ) {
	printf( "Going to the movies" );
	} else {
	printf( "Staying home" );
	}

PHP:

	<?php

	if ( $weatherIsSunny && ! $weatherIsRaining && ! $isWorking ) {
	echo 'Going to the festival';
	} else if ( $movieIsPlaying ) {
	echo 'Going to the movies';
	} else {
	echo 'Staying home';
	}

Python:

	if weatherIsSunny and not weatherIsRaining and not isWorking :
	print('Going to the festival')
	elif ( movieIsPlaying ) :
	print('Going to the movies')
	else :
	print('Staying home')

JavaScript:

	if ( weatherIsSunny && ! weatherIsRaining && ! isWorking ) {
	console.log( "Going to the festival" );
	} else if ( movieIsPlaying ) {
	console.log( "Going to the movies" );
	} else {
	console.log( "Staying home" );
	}