Variable naming rules in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

PHP Variable Naming: Output Check

What is the output of this PHP code snippet?

PHP

<?php
$var1 = 10;
$_var2 = 20;
$3var = 30;
echo $var1 + $_var2;
?>

A Syntax error

B 30

C 50

D Notice: Undefined variable

💡 Hint

Remember PHP variable names cannot start with a number.

In PHP, variable names must start with a letter or underscore. $3var starts with a digit, causing a syntax error.

❓ Predict Output

intermediate

PHP Variable Naming: Case Sensitivity

What will be the output of this PHP code?

PHP

<?php
$Var = 5;
$var = 10;
echo $Var + $var;
?>

A 15

B 10

C 5

D Undefined variable error

💡 Hint

PHP variable names are case sensitive.

PHP treats $Var and $var as two different variables. So 5 + 10 = 15.

❓ Predict Output

advanced

PHP Variable Naming: Valid or Invalid?

Which variable name is invalid in PHP?

A $_userName

B $user_name

C $user-name

D $UserName123

💡 Hint

PHP variable names cannot contain hyphens.

Hyphens are not allowed in PHP variable names because they are interpreted as minus operators.

❓ Predict Output

advanced

PHP Variable Naming: Output Prediction

What will this PHP code output?

PHP

<?php
$var = 1;
$Var = 2;
$VAR = 3;
echo $var + $Var + $VAR;
?>

A 1

B 3

C Undefined variable error

D 6

💡 Hint

PHP variable names are case sensitive.

Each variable is distinct: 1 + 2 + 3 = 6.

❓ Predict Output

expert

PHP Variable Naming: Complex Output

What is the output of this PHP code?

PHP

<?php
$var = 5;
$var_2 = 10;
$var2 = 15;
echo $var + $var_2 + $var2;
?>

A Syntax error

B 30

C 25

D Undefined variable error

💡 Hint

Underscores and numbers are allowed in variable names as long as they don't start with a number.

All three variables are valid and distinct. Their sum is 5 + 10 + 15 = 30.