Replacing a string in PHP involves substituting parts of a string with another string. Common methods include str_replace() for simple replacements, preg_replace() for pattern-based replacements, substr_replace() for positional replacements, and str_ireplace() for case-insensitive replacements. Each method serves different use cases.

Using str_replace()

A String is a collection of characters. The str_replace() is a built-in function in PHP and is used to replace all the occurrences of the search string or array of search strings by a replacement string or array of replacement strings in the given string or array respectively. We can replace the string with another by using PHP str_replace(). This method is case-sensitive, so the programmer has to take care of the case while programming and interpreting the output.

Syntax:

str_replace(substring,new_replaced_string,original_string);

We need to provide three parameters.

• substring is the string present in the original string that should be replaced
• replaced_string is the new string that replaces the substring.
• original_string is the input string.

Example 1: The following code replaces the string with another string.

<?php
//input string
$string="Geeks for Geeks";
//replace geeks in the string with computer
echo str_replace("Geeks","computer",$string);
?>

Output:

computer for computer

Example 2: The following code replaces the string with empty.

<?php
//input string
$string="Geeks for Geeks";
//replace geeks in the string with empty
echo str_replace("Geeks","",$string);
?>

for

<?php
//input string
$string="Geeks for Geeks";
//replace geeks in the string with value - 1
echo str_replace("Geeks",1,$string);
?>

1 for 1

<?php
$originalString = "Hello, World!";
$pattern = "/World/";
$replace = "PHP";
$newString = preg_replace($pattern, $replace, $originalString);
echo $newString . PHP_EOL; // Output: Hello, PHP!
?>

Hello, PHP!

<?php
// Original string
$originalString = "I have an apple and a banana.";

// Define the replacements in an associative array
$replacements = array(
    "apple" => "orange",
    "banana" => "grape"
);

// Use strtr() to replace substrings
$newString = strtr($originalString, $replacements);

// Output the new string
echo $newString . "\n"; // Output: I have an orange and a grape.
?>

I have an orange and a grape.