A string is a data type used in programming to represent a sequence of characters. These characters can be letters, numbers, spaces, symbols, etc. In many programming languages, a string is enclosed in single quotes (') or double quotes (").
String Concatenation
Concatenation is the process of joining two or more strings together.
<?php
$name = "John";
$lastname = "Smith";
// Concatenate strings with the "." operator
$fullname = $name . " " . $lastname;
echo $fullname; // Output: John Smith
?>
Here, the . operator is used to concatenate the variables $name and $lastname, separated by a space.
Size of a String
To find out the number of characters in a string, we use the strlen() function.
<?php
$text = "Hello, World!";
$size = strlen($text);
echo $size; // Output: 13
?>
The strlen() function counts the number of characters, including spaces and punctuation.
Replacing Part of a String
The str_replace() function replaces all occurrences of a substring within a string.
<?php
$sentence = "I like apples";
$newSentence = str_replace("apples", "bananas", $sentence);
echo $newSentence; // Output: I like bananas
?>
Here, the word "apples" was replaced with "bananas" in the original string.
Convert to Uppercase or Lowercase
You can use strtoupper()
to convert a string to uppercase and strtolower()
to convert it to lowercase.
<?php
$text = "Hello, World!";
$uppercase = strtoupper($text);
$lowercase = strtolower($text);
echo $uppercase; // Output: HELLO, WORLD!
echo $lowercase; // Output: hello, world!
?>
These functions are useful for standardizing the format of a string.
Get Part of a String
To extract part of a string, we use the substr()
function.
<?php
$text = "Learning PHP is fun!";
$part = substr($text, 9, 3);
echo $part; // Output: PHP
?>
Here, the substr()
function starts at position 9 (index 0) and returns 3 characters from there.
Remove Whitespace from the Beginning and End
The trim()
function removes whitespace (or other characters) from the beginning and end of a string.
<?php
$text = " Hello, World! ";
$clean = trim($text);
echo $clean; // Output: "Hello, World!"
?>
This function is useful for cleaning strings received from forms or user input.
Break a String into an Array
The explode()
function transforms a string into an array based on a delimiter.
<?php
$sentence = "PHP,JavaScript,Python";
$languages = explode(",", $sentence);
print_r($languages);
// Output: Array ( [0] => PHP [1] => JavaScript [2] => Python )
?>
Here, the explode()
function splits the string into several parts, using the comma as the delimiter.
Join Elements of an Array into a String
The implode()
function does the reverse of explode()
, joining the elements of an array into a string.
<?php
$languages = array("PHP", "JavaScript", "Python");
$sentence = implode(" | ", $languages);
echo $sentence; // Output: PHP | JavaScript | Python
?>
Find Position of Substring
The strpos()
function returns the position of the first occurrence of a substring within a string.
<?php
$sentence = "I like to program in PHP";
$position = strpos($sentence, "PHP");
echo $position; // Output: 23
?>
If the substring is not found, the function will return false
.
Reverse a String
To reverse a string, you can use strrev()
.
<?php
$text = "Hello, World!";
$reversed = strrev($text);
echo $reversed; // Output: !dlroW ,olleH
?>
You can run the code at https://onecompiler.com/php
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