default keyword in php

what does the keyword default开发者_C百科 in php do? there's no documentation on http://php.net/default, but i get an error when using it as a function name: »unexpected T_DEFAULT, expecting T_STRING«

what does it do/where can i find information about it?

default is part of the switch statement:

switch ($cond) {
  case 1:
    echo '$cond==1';
    break;
  case 2:
    echo '$cond==2';
    break;
  default:
    echo '$cond=="whatever"';
}

The default keyword is used in the switch construct:

$value = 'A';
switch ($value) {
case 'A':
case 'B':
    echo '$value is either A or B.';
break;
case 'C':
    echo '$value is C.';
break;
default:
    echo '$value is neither A, nor B, nor C.';
}

The default case matches anything that wasn’t matched by the other cases.

Adding to others answers:

default is a PHP keyword and keywords cannot be used as function name.

When you try:

function default () {
 ....
}

PHP expects to see a T_STRING ( an identifier) after the keyword function but sees a T_DEFAULT and flags a parse/syntax error:

unexpected T_DEFAULT, expecting T_STRING