Substring extraction in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What PHP function is used to extract a part of a string?

The substr() function is used to extract a substring from a string in PHP.

beginner

How do you extract the first 5 characters from a string $text in PHP?

Use substr($text, 0, 5); where 0 is the start position and 5 is the length.

intermediate

What happens if the start position in substr() is negative?

A negative start means counting from the end of the string backwards.

beginner

How to extract a substring from position 3 to the end of the string in PHP?

Use substr($string, 3); to get substring from index 3 to the end.

beginner

What does substr('Hello World', 6, 5) return?

It returns 'World', starting at index 6 and taking 5 characters.

Which function extracts a substring in PHP?

A strcut()

B substring()

C extract()

D substr()

The correct function to extract substrings in PHP is substr().

What does substr('abcdef', 2, 3) return?

A 'cde'

B 'bcd'

C 'def'

D 'abc'

Starting at index 2 ('c'), taking 3 characters gives 'cde'.

If the start index is negative in substr(), what happens?

A Returns empty string

B Starts from the beginning

C Starts from the end backwards

D Throws an error

A negative start index counts from the end of the string backwards.

How to get substring from index 4 to the end in PHP?

A substr($str, 4)

B substr($str, 0, 4)

C substr($str, -4)

D substr($str, 4, 0)

Using substr($str, 4) extracts from index 4 to the end.

What does substr('Hello', 1, 10) return?

A 'Hello'

B 'ello'

C 'H'

D Empty string

If length exceeds string end, it returns substring from start to end, here 'ello'.

Explain how to use the substr() function in PHP to extract parts of a string.

Think about start index and how length controls substring size.

Describe what happens when you use a negative start index in PHP's substr().

Imagine counting backwards from the string's last character.