In-depth understanding of the replacement function in php7

PHP is a widely used server-side programming language that plays a vital role in website development. New versions of PHP are constantly being released, providing better solutions for web developers. In this article, we will discuss replacement in PHP 7.

What is replacement?

Replacement refers to replacing the target string with a new string. In PHP, the replace function replaces the matching item in the text with a new string. This is useful when working with large text files, as it allows you to easily find a specific word, phrase, or character in a string and then replace it with new text.

In PHP, replacement operations can be completed by using multiple built-in functions. Next we will discuss these functions and their usage.

str_replace function

The str_replace function is one of the most commonly used replacement functions in PHP. It allows you to find matching text in a string and replace it with new text. Its syntax is as follows:

str_replace($search, $replace, $subject);

where $search is the string to be found, $replace is the new string to be replaced, and $subject is the string in which to perform the replacement operation.

For example, suppose we have a string "hello, world!" and we want to replace "world" with "php". We can use the following code to achieve this replacement:

$old_string = "hello, world!";
$new_string = str_replace("world", "PHP", $old_string);
echo $new_string;

The output result is "hello, PHP!".

str_ireplace function

The str_ireplace function is a case-insensitive version of the str_replace function. Its syntax is almost the same as str_replace function, but it is not case sensitive. For example:

$old_string = "hello, World!";
$new_string = str_ireplace("WORLD", "PHP", $old_string);
echo $new_string;

The output result is "hello, PHP!".

preg_replace function

The preg_replace function is an upgraded version of str_replace, which is most commonly used when processing regular expressions. The syntax of the preg_replace function is as follows:

preg_replace($pattern, $replacement, $subject);

where $pattern is the regular expression you want to search for, $replacement is the new string to be used to replace it, and $subject is where the replacement operation is to be performed. String.

Let's look at an example. Suppose we want to replace all "apple" with "orange" in the following string:

$string = "I have one apple, she has two apples, he has three apples.";
$new_string = preg_replace("/apple/i", "orange", $string);
echo $new_string;

Here, we have used the regular expression "/apple/i" where "i" means size insensitive Write, that is, search for all "apple" in the string and replace them with "orange". The output is "I have one orange, she has two oranges, he has three oranges."

strtr function

The strtr function is used to replace the specified character in a string with another character. Its syntax is as follows:

strtr($string, $old_char, $new_char);

Among them, $string is the string to be replaced, $old_char is the character to be replaced, and $new_char is the new character.

For example, suppose we have a string "Hello, World!" and we want to replace "o" with "P" and "W" with "h". We can use the following code to achieve this replacement:

$old_string = "Hello, World!";
$new_string = strtr($old_string, "oW", "Ph");
echo $new_string;

The output result is "HellP, phrld!".

Summary

In PHP 7, there are many ways to perform substitution operations. str_replace and str_ireplace are two of the most commonly used functions that allow you to find a specific word, phrase, or character in a string and replace it with new text. preg_replace allows you to use regular expressions for replacement operations, while the strtr function is used to replace a specified character in a string with another character. These functions are useful when you need to perform text replacement on a large number of text files.

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