Replace

$MyString = str_replace('ReplaceThis', 'WithThis', $MyString);

$domain = str_replace('www.', '', $domain);     //Remove leading www. from $domain

Case insensitive

str_ireplace() is a case-insensitive version of str_replace()

$MyString= str_ireplace("one", "1", $MyString);    //Replace "OnE" with "1"

Replace whitespace

Replace single and multiple occurrences of white space with a comma

  $MyString= preg_replace('/\s+/', ',', $MyString);    //Replace single and multiple occurrence of white space with a comma

Pad string to fixed length

$MyString = "Apple"
$RequiredLength = 26;
$PadWithString = "*~*"
$MyString = str_pad($MyString, $RequiredLength, $PadWithString, STR_PAD_BOTH);
  //Will give: "*~**~**~**Apple*~**~**~**~"

$MyString = str_pad($MyString, $RequiredLength, $PadWithString, STR_PAD_RIGHT);
  //Will give: "Apple*~**~**~**~**~**~**~*"

$MyString = str_pad($MyString, $RequiredLength, " ", STR_PAD_RIGHT);
  //Will give: "Apple                     "