Decision Branching – switch/case

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There are times when you need to make multiple decisions. In these cases, the level of branches grows. Programming languages give you an alternative with the switch/case construct.

Your key takeaways are:

Switch/case more concise representation of an if/else if/else conditional control statement
Don’t have to repeat the conditional comparison in each branch
Easier to read
Gives you control to determine what code to run (execute)

Study Notes

Below is some pseudocode to show a multistate decision tree:

	if ( weatherCondition == 'sunny' )
	go for a walk
	else if ( weatherCondition == 'raining' )
	dance in the rain
	else if ( weatherCondition == 'foggy' )
	sound the fog horn
	else if ( weatherCondition == 'snowing' )
	build a snowman
	else
	read a book

view raw cs0110-3.4-mulit-decision-tree hosted with ❤ by GitHub

Convert the multi-state decision tree into a less verbose format with a switch/case statement:

	switch ( weatherCondition )
	case 'sunny':
	go for a walk
	break;
	case 'raining':
	dance in the rain
	break;
	case 'foggy':
	sound the fog horn
	break;
	case 'snowing':
	build a snowman
	break;
	default:
	read a book

view raw cs0110-3.4-switch-case.txt hosted with ❤ by GitHub

Anatomy of the Switch Statement

	switch ( expression ) // expression's value is matched to each of the case statements.
	case value1: // If the expression matches this value, then do this block of code.
	// do something
	break // stop and jump out of the switch
	case value2:
	// do something
	break
	case value3:
	// do something
	break
	default: // "else" catch all code block If none of the others match, then do this one.
	// do something

view raw cs0110-3.4-anatomy.txt hosted with ❤ by GitHub

Switch Statements in Other Languages

	switch ( weatherCondition ) {
	case 'sunny':
	printf("go for a walk");
	break;
	case 'raining':
	printf("dance in the rain");
	break;
	case 'foggy':
	printf("sound the fog horn");
	break;
	case 'snowing':
	printf("build a snowman");
	break;
	default:
	printf("read a bookâ€);
	}

view raw cs0110-3.4-c hosted with ❤ by GitHub

	switch ( weatherCondition ) {
	case "sunny":
	document.write("go for a walk");
	break;
	case raining":
	document.write("dance in the rain");
	break;
	case "foggy:
	document.write("sound the fog horn");
	break;
	case "snowing":
	document.write("build a snowman");
	break;
	default:
	document.write("read a bookâ€);
	}

view raw cs0110-3.4-js hosted with ❤ by GitHub

	switch ( $weatherCondition ) {
	case 'sunny':
	echo 'go for a walk';
	break;
	case 'raining':
	echo 'dance in the rain';
	break;
	case 'foggy':
	echo 'sound the fog horn;
	break;
	case 'snowing':
	echo 'build a snowman';
	break;
	default:
	echo 'read a book';
	}

view raw cs0110-3.4-php hosted with ❤ by GitHub

Whoever says that coding is hard, just smack them.

Episodes

Total Lab Runtime: 02:17:55

1 Lab Introductionfree 06:21
2 User-Friendly Expression of Informationfree 22:42
3 Fundamentals of Syntaxfree 08:57
4 Decision Branching - if/then/elsefree 10:39
5 Decision Branching – switch/casefree 07:47
6 Basics of Iterationfree 14:14
7 Iteration in Practicefree 12:51
8 Order of Executionfree 10:55
9 Abstractionfree 11:45
10 Scoping – Who Can Communicate With Whomfree 31:44

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Decision Branching – switch/case

Lab: Building Blocks of Programming

Study Notes

Anatomy of the Switch Statement

Switch Statements in Other Languages

Episodes

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