What is the function of the replace function in PHP?

In PHP, the purpose of the replace function is to substitute specified characters or patterns in a string. In other words, the replace function is used to search for specified characters or patterns within a string and replace them with new specified characters or patterns.

The syntax of the replace function is as follows:

string replace ( mixed $search , mixed $replace , mixed $subject [, int &$count ] )

Explanation of parameters:

1. $search: the string or pattern to search and replace.
2. $replace: replace the string or pattern matched in $search with a new string.
3. $subject: String that requires search and replace operations.
4. $count: Optional parameter, if provided, returns the number of replacements made.

There is no need to worry about the situation.

$str = "Hello World!";
$newStr = str_replace("World", "PHP", $str);
echo $newStr;  // 输出：Hello PHP!

In the above example, the replace function replaces “World” with “PHP” in the string, assigns the replaced string to the $newStr variable, and finally outputs the replaced string.