PHP/String/substr replace

By supplying no start or length arguments, the string will be added to the beginning

 
<?php
  $mystring = substr_replace("Hello World", "H3110 W0r1d!", 0, 0);
  echo $mystring . "<br />"; //Echos H3110 W0r1d!Hello World
  
  $mystring = substr_replace("Hello World", "0 w0", 4, 4);
  echo $mystring; //Echos Hell0 w0rld.
  
?>

PHP has two main functions for performing simple search-and-replace operations. The first one is substr_replace

 
<?php
    $haystack = "this is a test";
    $newstr = substr_replace ($haystack, "sad", 6, 5); 
    echo "$newstr\n";
?>

Replacing a Portion of a String Using substr_replace()

 
<?
    $membership = "asdfasdf";
    $membership = substr_replace( $membership, "00", 2, 2);
    print "New membership number: $membership<br/>";
?>

Replacing a substring with substr_replace()

 
$new_string = substr_replace($old_string,$new_substring,$start);
$new_string = substr_replace($old_string,$new_substring,$start,$length);

Replacing Substrings: string substr_replace ( string str, string replacmnt, int start [, int len] )

 
<?php 
$mystring = substr_replace("Hello World", "asdf", 0, 0); 
echo $mystring . "<br />"; 
$mystring = substr_replace("Hello World", "0 w0", 4, 4); 
echo $mystring; 

?>

substr_replace() function replaces the string with replacement.

 
Its syntax is: string substr_replace (string string, string replacement, int start [, int length])
If start is positive, replacement starts at character start.
If start is negative, replacement starts at (string length - start).
If length is positive, replacement will be length characters long.
If length is negative, replacement will end at (string length - length) characters.
<?
$favs = "is good";
$name = "A";
$favs = substr_replace($favs, $name, 0, 0);
print $favs;
?>

substr_replace.php

 
<?php
   $ccnumber = "1234567899991111";
   echo substr_replace($ccnumber,"************",0,12);
?>