String concatenation operator in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code using concatenation?

Consider the following PHP code snippet. What will it print?

PHP

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

A Hello World!

B HelloWorld!

C Hello World

D Hello.World!

💡 Hint

Remember the dot (.) operator joins strings exactly as written.

The dot operator concatenates strings exactly. Here, $a and $b are joined with a space and an exclamation mark, producing 'Hello World!'.

❓ Predict Output

intermediate

What does this PHP code output with mixed concatenation and addition?

Look at this PHP code. What will it output?

PHP

<?php
$x = 5;
$y = "10";
echo $x + $y . " apples";
?>

A 510 apples

B 15 apples

C 5 apples

D TypeError

💡 Hint

PHP converts strings to numbers when using + operator.

The + operator adds numbers, so $y is converted from "10" to 10. Then 5 + 10 = 15. The dot concatenates '15' with ' apples'.

🔧 Debug

advanced

Which option causes a syntax error in PHP string concatenation?

Identify which code snippet will cause a syntax error when run.

A <?php echo "Hello" .+ "World"; ?>

B <?php echo "Hello" + "World"; ?>

C <?php echo "Hello" . " " . "World"; ?>

D <?php echo "Hello" . "World"; ?>

💡 Hint

Check the operator symbols carefully.

Option A uses '.+' which is not a valid operator in PHP, causing a syntax error.

❓ Predict Output

advanced

What is the output of this PHP code with concatenation assignment?

What will this PHP code print?

PHP

<?php
$str = "Good";
$str .= " Morning";
$str .= "!";
echo $str;
?>

A Good . Morning!

B GoodMorning!

C Good Morning

D Good Morning!

💡 Hint

The '.=' operator adds to the existing string.

The '.=' operator appends strings. So $str becomes 'Good Morning!' after both concatenations.

🧠 Conceptual

expert

How many items are in the resulting array after this PHP code runs?

What is the count of elements in the array after this code executes?

PHP

<?php
$arr = [];
$arr['a'] = 'Hello';
$arr['b'] = 'World';
$arr['a'] .= ' PHP';
?>

A 1

B 3

C 2

D 0

💡 Hint

Appending to an existing key does not add new elements.

The array has keys 'a' and 'b'. The '.=' operator appends to the value at 'a' but does not add new keys. So total elements remain 2.