Using PHP substr_replace() to Replace or Insert Substrings

The PHP substr_replace() function replaces a portion of a string with another string.

substr_replace() Function Syntax

substr_replace(string $string, string $replacement, int $start [, int $length]): string

Parameters: $string is the original string, $replacement is the string to insert, $start is the position where replacement begins, and optional $length specifies how many characters to replace. The function returns the modified string.

substr_replace() Function Examples

Replace characters at a specified position

$text = "Hello, world!";<br/>$text = substr_replace($text, "PHP", 7, 6);<br/>echo $text; // outputs "Hello, PHP!"

This example replaces six characters starting at position 7 with "PHP", resulting in "Hello, PHP!".

Replace a string at a specified position

$text = "Hello, world!";<br/>$text = substr_replace($text, "PHP", 7, 5);<br/>echo $text; // outputs "Hello, PHP!"

Here the length is set to 5, so the five characters from position 7 are replaced by "PHP".

Insert a string at the beginning of a string

$text = "world!";<br/>$text = substr_replace($text, "Hello, ", 0, 0);<br/>echo $text; // outputs "Hello, world!"

The string "Hello, " is inserted at the start, producing "Hello, world!".

Insert a string at the end of a string

$text = "Hello, ";<br/>$text = substr_replace($text, "world!", strlen($text), 0);<br/>echo $text; // outputs "Hello, world!"

By using the length of the original string as the start position, "world!" is appended to the end.

Insert a string in the middle of a string

$text = "Hello, world!";<br/>$text = substr_replace($text, "beautiful ", 7, 0);<br/>echo $text; // outputs "Hello, beautiful world!"

The word "beautiful " is inserted before position 7, resulting in "Hello, beautiful world!".

Summary

The substr_replace() function is a versatile tool for string manipulation in PHP, allowing replacement of characters or substrings at any position and insertion of strings at the beginning, middle, or end of a string.

PHP Learning Recommendations

Various tutorial links are provided for further learning.