What is the usage of the str_replace function in PHP?

The str_replace function in PHP is used to replace specified characters or character sets in a string. Its basic usage can be demonstrated as follows:

replace all occurrences of the search string with the replace string in the subject string

Among them:

1. search: characters or sets of characters that need to be replaced. It can be a single string or an array of strings.
2. replacement: characters or character set used for substitution. It can be a single string or an array of strings.
3. subject: The string that needs to undergo replacement operation. It can be a single string or an array of strings.

The function searches for ‘search’ in the subject and replaces all matches with ‘replace’, before finally returning the replaced string.

For example, consider the following code:

$text = "Hello, world!";
$newText = str_replace("world", "PHP", $text);
echo $newText;

The output result is:

Hello, PHP!

In the above example, the str_replace function replaces the “world” in the string $text with “PHP” and assigns the replaced string to $newText. Finally, the $newText is outputted using the echo statement.

In addition to replacing individual characters or character sets, the str_replace function can also be used for bulk replacements. For example:

$text = "I like apples and bananas.";
$search = array("apples", "bananas");
$replace = array("oranges", "grapes");
$newText = str_replace($search, $replace, $text);
echo $newText;

The output result is:

I like oranges and grapes.

In the example above, the str_replace function replaces “apples” with “oranges” and “bananas” with “grapes” within the $text. The final output is the replaced string $newText.