Variable naming rules in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What character must a PHP variable name start with?

A PHP variable name must start with a dollar sign ($). For example, $variable is valid.

beginner

Can PHP variable names contain spaces or special characters like @ or #?

No, PHP variable names cannot contain spaces or special characters like @ or #. They can only contain letters, numbers, and underscores after the initial $.

beginner

Are PHP variable names case-sensitive?

Yes, PHP variable names are case-sensitive. For example, $Name and $name are two different variables.

beginner

Is $2ndValue a valid PHP variable name? Why or why not?

No, $2ndValue is not valid because variable names cannot start with a number after the dollar sign. The first character after $ must be a letter or underscore.

beginner

What characters are allowed in PHP variable names after the initial $?

After the initial $, PHP variable names can contain letters (a-z, A-Z), numbers (0-9), and underscores (_). They cannot start with a number.

Which of the following is a valid PHP variable name?

A $user_name

B userName

C $9lives

D $user-name

Only option C is valid. It starts with $ followed by a letter or underscore, and uses only allowed characters (letters, numbers, and underscore). A starts with a number after $, B lacks $, and D contains a hyphen.

Are PHP variable names case-sensitive?

A Only in some PHP versions

B No, $Var and $var are the same variable

C Yes, $Var and $var are different variables

D Only for variables starting with underscore

PHP variable names are case-sensitive, so $Var and $var refer to different variables.

What is the first character of every PHP variable name?

A $

B _

C a letter

D a number

Every PHP variable name must start with a dollar sign ($).

Which character is NOT allowed in PHP variable names after the $?

A a

B 9

C _

D -

Hyphens (-) are not allowed in PHP variable names.

Is this variable name valid in PHP? $_myVar123

A No, because it contains uppercase letters

B Yes

C No, because it contains numbers

D No, because it starts with underscore

Variable names can start with an underscore and contain numbers and uppercase letters.

Explain the rules for naming variables in PHP.

Think about what characters are allowed and the importance of the $ sign.

Why is $2ndValue not a valid variable name in PHP? What would be a valid alternative?

Focus on the first character after the dollar sign.