Trim functions in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the trim() function do in PHP?

The trim() function removes whitespace or other predefined characters from the beginning and end of a string.

beginner

How do ltrim() and rtrim() differ from trim()?

ltrim() removes whitespace or characters only from the start (left) of a string, while rtrim() removes them only from the end (right). trim() removes from both ends.

beginner

What is the default character set removed by trim() if no second argument is given?

By default, trim() removes whitespace characters including space, tab, newline, carriage return, NULL byte, and vertical tab.

intermediate

How can you remove specific characters using trim()?

You can pass a second argument to trim() listing the characters to remove. For example, trim($str, "xyz") removes 'x', 'y', and 'z' from both ends of $str.

beginner

What will rtrim("Hello World!!!", "!") return?

It will return "Hello World" because rtrim() removes all trailing exclamation marks from the right end of the string.

Which PHP function removes whitespace from both the start and end of a string?

A trim()

B ltrim()

C rtrim()

D strip()

trim() removes whitespace from both ends, while ltrim() and rtrim() remove from left or right only.

What does ltrim(" Hello") return?

A "Hello "

B "Hello" with leading spaces

C "Hello"

D " Hello"

ltrim() removes whitespace from the start (left), so leading spaces are removed.

How do you remove only trailing dots from a string $str?

A trim($str, ".")

B rtrim($str, ".")

C ltrim($str, ".")

D strip($str, ".")

rtrim() removes characters from the right end only.

Which characters are removed by default by trim()?

A All non-alphanumeric characters

B Spaces and tabs only

C Only spaces

D Whitespace characters like space, tab, newline, carriage return

By default, trim() removes all common whitespace characters.

What will trim("***Hello***", "*") return?

A "Hello"

B "***Hello"

C "Hello***"

D "***Hello***"

The trim() call removes all '*' characters from both ends.

Explain how trim(), ltrim(), and rtrim() work and when you might use each.

Think about cleaning spaces or unwanted characters from user input.

Describe how to remove specific characters from the start and end of a string using PHP trim functions.

Remember the second argument is a list of characters to remove.