Conditionals and Logic in PHP

Learn about the boolean data type, conditionals, `switch` statements, the ternary operator, comparison operators, and logical operators!

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Key Concepts

Review core concepts you need to learn to master this subject

PHP Boolean Values

PHP If Statements

PHP else statement

PHP comparison operators

PHP elseif statements

PHP switch statement

PHP ternary operator

PHP Truthy and Falsy

PHP Boolean Values

// booleans
$is_true = TRUE;
$is_false = FALSE;

echo gettype($is_true); 
// Prints: boolean
echo gettype($is_false); 
// Prints: boolean

PHP Boolean values are either TRUE or FALSE, which are the only members of the boolean type

Booleans and Comparison Operators

Lesson 1 of 2

1
Introduction
Have you ever noticed that hyperlinks change color after you click them? If the link has been clicked, then the web browser renders it in purple, rather than blue. The programming concept that …
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2
If Statements
We’re going to learn about a specific type of conditional called an if statement. An if statement follows this basic structure: if (/some condition/) { // Do something… } The parentheses ho…
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3
Comparison Operators
The condition, or expression, in an if statement can hold a boolean value—like TRUE or FALSE, a variable assigned to one of those values, or an expression that evaluates to TRUE or FALSE. Just …
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4
Identical and Not Identical Operators
In this exercise we’re going to learn a few more comparison operators and see how we can use them to compare more than just number values. The identical operator (===) will return TRUE if the lef…
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5
Elseif Statements
So far, we’ve been writing conditionals that can only handle one condition. If that condition is met, we do one thing, otherwise we do something else. This only allows us one or two courses…
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6
Switch Statement
We often want to compare a value, expression, or variable against many different possible values and run different code depending on which it matches. We can use a series of if/elseif statements wh…
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7
Switch Statements: Fall through
In the previous exercise, we taught you to use the keyword break after the block for each case. Without the keyword break, not only will the first matching case’s block run, but so will all the co…
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8
Ternary Operator
PHP offers a short-hand syntax to conditionally return a value. Before learning it, let’s consider some example code: $isClicked = FALSE; if ( $isClicked ) { $link_color = “purple”; } else { $…
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9
Truthy and Falsy
So far in our conditionals, we’ve been dealing with expressions that would evaluate to boolean values in any context. In practice, any value or expression in the condition will be converted…
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10
User Input: readline()
The outcomes of programs we’ve been writing so far have been predetermined. Unless we manually change our code, it will produce the same results each time it’s run. But this isn’t very realistic. P…
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11
Review
Woah! We covered a lot in this lesson. Good work. Let’s review what we learned: + Conditionals make it possible for programs to decide how to react to a wide variety of situations. + if statements …
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