If statement execution flow in PHP - Step-by-Step Execution

Concept Flow - If statement execution flow

Start

↓

Evaluate condition

↓

Execute if-block

↓

Continue

↓

Skip if-block

↓

Continue

The program checks the condition. If true, it runs the code inside the if-block. If false, it skips it and continues.

Execution Sample

PHP

<?php
$age = 20;
if ($age >= 18) {
    echo "Adult";
}
?>

Checks if age is 18 or more, then prints 'Adult' if true.

Execution Table

Step	Condition ($age >= 18)	Result	Branch Taken	Output
1	20 >= 18	True	Execute if-block	Adult
2	End of if statement	-	Continue	-

💡 Condition true, executed if-block and printed 'Adult', then continued.

Variable Tracker

Variable	Start	After Step 1	Final
$age	20	20	20

Key Moments - 2 Insights

Why does the code inside the if-block run only when the condition is true?

Because the if statement checks the condition first (see execution_table step 1). If true, it runs the block; if false, it skips it.

What happens if the condition is false?

The program skips the if-block and continues (not shown here, but see concept_flow and execution_table branch 'No').

Visual Quiz - 3 Questions

Look at the execution table, what is the output at step 1?

A Error

B Adult

C No output

D 20

💡 Hint

Check the 'Output' column in execution_table row for step 1.

At which step does the program decide to skip the if-block?

A Step 1

B Step 2

C Never in this example

D Before step 1

💡 Hint

Look at the 'Branch Taken' column in execution_table; the if-block is executed at step 1.

If $age was 16, how would the execution_table change at step 1?

A Condition would be false, branch would skip if-block

B Condition would be true, branch would execute if-block

C Output would be 'Adult'

D Program would crash

💡 Hint

Refer to the condition evaluation in execution_table and concept_flow for false branch.

Concept Snapshot

if (condition) {
  // code runs if condition is true
}

Checks condition once.
Runs block only if true.
Skips block if false.
Then continues program.

Full Transcript

This visual shows how an if statement works in PHP. The program starts and checks the condition inside the if statement. If the condition is true, it runs the code inside the if-block. If false, it skips that code and continues. In the example, the variable $age is 20. The condition $age >= 18 is true, so the program prints 'Adult'. The variable $age stays the same throughout. Beginners often wonder why the code runs only when the condition is true; this is because the if statement controls that flow. If the condition was false, the code inside would be skipped. The quiz questions help check understanding of these steps.