String split and explode in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the explode() function do in PHP?

The explode() function splits a string into an array using a specified delimiter.

beginner

How do you split a string by spaces using explode()?

Use explode(' ', $string) to split the string at each space character.

intermediate

What is the difference between explode() and str_split()?

explode() splits a string by a delimiter into an array of substrings.
str_split() splits a string into an array of single characters or fixed-length chunks.

beginner

What will explode(',', 'apple,banana,orange') return?

It returns an array: ['apple', 'banana', 'orange'] splitting the string at each comma.

intermediate

Can explode() handle an empty delimiter?

No, explode() requires a non-empty string as the delimiter. Passing an empty string will cause a warning.

Which function splits a string into an array by a delimiter in PHP?

A substr()

B implode()

C str_replace()

D explode()

explode() splits strings by a delimiter. implode() joins array elements into a string.

What does explode('-', '2024-06-15') return?

A ['2024', '06', '15']

B '2024-06-15'

C ['2024-06-15']

D ['2024', '-06', '-15']

The string is split at each dash, producing an array of three parts.

What happens if the delimiter is not found in the string when using explode()?

A Throws an error

B Returns an empty array

C Returns an array with the original string as the only element

D Returns null

If delimiter is missing, explode() returns an array containing the whole string.

Which function splits a string into single characters or fixed-length chunks?

A str_split()

B explode()

C substr()

D implode()

str_split() splits strings into characters or chunks, unlike explode() which uses delimiters.

What is the correct way to split a CSV string into an array?

A explode(' ', $csvString)

B explode(',', $csvString)

C str_split($csvString)

D implode(',', $csvString)

CSV values are separated by commas, so use explode(',', $csvString).

Explain how the explode() function works and give an example.

Think about how you cut a sentence into words using spaces.

Describe the difference between explode() and str_split() in PHP.

One splits by a character or string, the other by length.

Practice

1. What does the PHP function explode() do?

easy

A. It replaces parts of a string with another string.

B. It joins array elements into a string.

C. It counts the number of characters in a string.

D. It splits a string into an array using a delimiter.

Solution

1. Step 1: Understand the purpose of explode()

   The explode() function takes a string and splits it into pieces based on a delimiter.

2. Step 2: Recognize the output type

   It returns an array containing the split parts of the original string.

3. Final Answer:

   It splits a string into an array using a delimiter. -> Option D

4. Quick Check:

   explode() = split string to array [OK]

Hint: explode() breaks strings into arrays by delimiter [OK]

Common Mistakes:

• Confusing explode() with implode() which joins arrays
• Thinking explode() returns a string instead of an array
• Assuming explode() modifies the original string

2. Which of the following is the correct syntax to split the string 'apple,banana,orange' by commas using explode()?

easy

A. explode(' ', 'apple,banana,orange')

B. explode('apple,banana,orange', ',')

C. explode(',', 'apple,banana,orange')

D. explode('apple', 'banana,orange')

Solution

1. Step 1: Identify explode() parameter order

   The first parameter is the delimiter (separator), the second is the string to split.

2. Step 2: Match parameters to the example

   To split by commas, delimiter is ',' and string is 'apple,banana,orange'. So syntax is explode(',', 'apple,banana,orange').

3. Final Answer:

   explode(',', 'apple,banana,orange') -> Option C

4. Quick Check:

   explode(delimiter, string) = explode(',', 'apple,banana,orange') [OK]

Hint: Delimiter is first, string second in explode() [OK]

Common Mistakes:

• Swapping the order of parameters
• Using wrong delimiter like space instead of comma
• Passing parts of string as delimiter

3. What is the output of the following PHP code?

$str = "one,two,three,four";
$result = explode(",", $str, 3);
print_r($result);

medium

A. Array ( [0] => one [1] => two [2] => three,four )

B. Array ( [0] => one [1] => two [2] => three )

C. Array ( [0] => one,two [1] => three [2] => four )

D. Array ( [0] => one [1] => two [2] => three [3] => four )

Solution

1. Step 1: Understand explode() with limit parameter

   The third parameter limits the number of pieces. Here, limit=3 means maximum 3 parts.

2. Step 2: Apply limit to splitting

   The string splits at first two commas: 'one', 'two', and the rest 'three,four' stays as last part.

3. Final Answer:

   Array ( [0] => one [1] => two [2] => three,four ) -> Option A

4. Quick Check:

   explode(',', string, 3) limits to 3 parts [OK]

Hint: Limit splits into max parts; last part keeps rest [OK]

Common Mistakes:

• Ignoring the limit parameter effect
• Expecting all parts split regardless of limit
• Confusing array keys or values

4. Identify the error in this PHP code snippet:

$data = "red|green|blue";
$colors = explode($data, "|");
print_r($colors);

medium

A. The delimiter "|" is invalid in explode().

B. The delimiter and string parameters are swapped in explode().

C. explode() cannot split strings with pipe characters.

D. print_r() cannot print arrays.

Solution

1. Step 1: Check explode() parameter order

   explode() expects delimiter first, then the string to split.

2. Step 2: Analyze given code

   Code uses explode($data, "|"), which swaps parameters incorrectly.

3. Final Answer:

   The delimiter and string parameters are swapped in explode(). -> Option B

4. Quick Check:

   explode(delimiter, string) correct order [OK]

Hint: Delimiter always first, string second in explode() [OK]

Common Mistakes:

• Swapping parameters causing wrong output or errors
• Thinking delimiter must be a letter only
• Assuming print_r() can't print arrays

5. You have a string "name:age:city:country". You want to split it into exactly 3 parts where the last part contains everything after the second colon. Which explode() call achieves this?

hard

A. explode(':', $string, 3)

B. explode(':', $string, 2)

C. explode(':', $string, 4)

D. explode(':', $string)

Solution

1. Step 1: Understand the limit parameter in explode()

   Limit defines max number of parts. If limit=3, explode splits at first two delimiters, last part has rest.

2. Step 2: Apply to given string

   With limit=3, parts are: 'name', 'age', and 'city:country' combined as last part.

3. Final Answer:

   explode(':', $string, 3) -> Option A

4. Quick Check:

   Limit 3 splits into 3 parts, last part keeps rest [OK]

Hint: Use limit=3 to get 3 parts, last part keeps remaining string [OK]

Common Mistakes:

• Using limit=2 which gives only 2 parts
• Using no limit which splits all parts
• Confusing limit with number of delimiters