String concatenation operator in PHP - Step-by-Step Execution

Concept Flow - String concatenation operator

Start

↓

Two strings

↓

Use . operator

↓

Combine strings

↓

Result: concatenated string

↓

End

This flow shows how two strings are joined using the dot (.) operator to create one combined string.

Execution Sample

PHP

<?php
$a = "Hello";
$b = " World";
$c = $a . $b;
echo $c;
?>

This code joins two strings "Hello" and " World" using the dot operator and prints the result.

Execution Table

Step	Action	Variable	Value	Output
1	Assign string	$a	"Hello"
2	Assign string	$b	" World"
3	Concatenate $a and $b	$c	"Hello World"
4	Print $c	Output		Hello World

💡 End of script after printing concatenated string.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
$a	undefined	"Hello"	"Hello"	"Hello"	"Hello"
$b	undefined	undefined	" World"	" World"	" World"
$c	undefined	undefined	undefined	"Hello World"	"Hello World"

Key Moments - 2 Insights

Why do we use the dot (.) instead of plus (+) to join strings in PHP?

In PHP, the dot (.) is the operator for joining strings. Using plus (+) tries to add numbers, so it won't join strings. See step 3 in the execution_table where $c is assigned using the dot.

What happens if one of the variables is not a string?

PHP converts non-string values to strings when using the dot operator. So concatenation still works, but the value is converted first.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of $c after step 3?

A " World"

B "Hello"

C "Hello World"

D undefined

💡 Hint

Check the 'Value' column for $c at step 3 in the execution_table.

At which step is the output produced?

A Step 1

B Step 4

C Step 2

D Step 3

💡 Hint

Look at the 'Output' column in the execution_table to find when output appears.

If $b was assigned the number 5 instead of a string, what would $c be after concatenation?

A "Hello5"

B "Hello World"

C Error

D "Hello 5"

💡 Hint

Recall that PHP converts numbers to strings when using the dot operator, as explained in key_moments.

Concept Snapshot

PHP uses the dot (.) operator to join strings.
Syntax: $combined = $str1 . $str2;
It converts non-strings to strings automatically.
Plus (+) is NOT for strings in PHP.
Result is a new combined string.

Full Transcript

This visual trace shows how PHP joins two strings using the dot operator. First, variables $a and $b get string values. Then $c is assigned by joining $a and $b with the dot. Finally, $c is printed, showing the combined string. The dot operator is special for strings in PHP and converts other types if needed. The output appears only after printing $c. This helps beginners see each step clearly.