how to replace characters in string in php code example

Example 1: php str_replace

<?php
//str_replace("Original Value", "Value to be replaced", "String");
$result = str_replace("1", "2", "This is number 1");
// Output: This is number 2
?>

Example 2: str_replace php variable

$var1 = 'hello_john';
$var2 = str_replace("_", "-", $var1);
echo $var2; // hello-john