How to convert a given substring into * in PHP (case sensitive)

In the previous article "How does PHP replace a substring of a certain length with a * sign" we introduced a method of string replacement. This time we introduce another method for string replacement and see how this method replaces a given substring with an * sign.

The method introduced above is to perform string replacement by giving the replacement start position and replacement length. This article introduces another method: directly give the substring that needs to be replaced for replacement. Because the replacement substring is directly set, there will be a case problem, which is divided into two situations: case sensitive and Case insensitivity. Today we will introduce the case-sensitive replacement method.

Let’s take a look at the following example:

<?php
$str = &#39;hello,world,Hello,World&#39;;
$replace = &#39;*&#39;;
$search1 = &#39;hello&#39;;
$search2 = &#39;world&#39;;
echo str_replace($search1, $replace, $str)."<br>";
echo str_replace($search2, $replace, $str)."<br>";
?>

Observe the above code, we need to change the “hello” in the string $str " and "world" values ​​are replaced with *; and $str in the string "hello,world,Hello,World" There are two types of replacement substrings, the only difference lies in the size of the first letter.

Because the str_replace() function is used to perform string replacement, this function is case-sensitive and case-sensitive, so it only searches for " in the string $str" hello" and "world" values, and replace them with * numbers respectively. So the output result is:

function str_replace() that implements this function.

str_replace($search,$replace,$string,$count)The function can replace some characters in the string in a case-sensitive manner; the function accepts three required parameters $search (the substring to search for), $replace (the value to be replaced), $string (the string), and an optional parameter $ count (a variable).

$count.

$count needs to be set to a variable to count and return the number of times replacement is performed. To put it simply, by setting the parameter $count, you can know how many replacements have been performed in total.

$count through code examples.

<?php
header("Content-Type: text/html;charset=utf-8");    //设置字符编码
$str = &#39;hello,world,Hello,world&#39;;
$replace = &#39;*&#39;;
$search1 = &#39;hello&#39;;
$search2 = &#39;world&#39;;
$search3 = &#39;,&#39;;
echo str_replace($search1, $replace, $str,$i)."<br>";
echo  "一共执行了  $i"." 次替换<br><br>";

echo str_replace($search2, $replace, $str,$i)."<br>";
echo  "一共执行了  $i"." 次替换<br><br>";

echo str_replace($search3, $replace, $str,$i)."<br>";
echo  "一共执行了  $i"." 次替换<br>";
?>

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