KEYWORD

Keyword

switch (expr) block

DESCRIPTION

Branch to the case label in statement that matches expr. If no matching case label is found (by value or by type), branch to the default label in statement.

Keyword: case

case expr [.. expr2]: block

A case label has the form

case expr_n :

where expr_n must be constant, or the form

case expr_n1 .. expr_n2 :

where expr_n1 and expr_n2 must be numeric constants and expr_n1 < expr_n2.

Either all case labels have to be strings or all have to be numeric. Only 0 is special: it is allowed in a switch statement where all other labels are strings.

Keyword: default

default: block

A default label has the form

default :

The default label defaults to the end of statement if not given explicitly.

Whenever a ‘break’ statement is executed inside ‘statement’ a branch to the end of the switch statement is performed.

USAGE

switch(random(100)) {
  case 0 .. 22 : write("Nothing happens"); break;
  case 23 .. 27 :
    write("You are surrounded by a golden glow");
    this_player()->heal_self(random(3));
    break;
  case 28 .. 32 :
    write("The water was poisoned!\n");
    this_player()->add_exp(this_player()->hit_player(random(4)));
    break;
  case 33 : write("You hear a voice whispering: "+random_hint());
  /* fall through */
  case 34 :
    write(
      "While you didn't pay attention, a water demon "
      "snatches a coin out of your purse!\n"
    );
    this_player()->add_money(-1);
    break;
  default : write "You hear some strange noises\n"; break;
  case 42 : return;
  case 99 : write("It tastes good.\n";
}

Note

In C, the grammar for switch is:

switch (expr) statement

allowing constructs like:

switch (expr)
  while (expr2)
  {
  case 1: ...
  case 2: ...
  }

In LPC a switch must be followed by a block that contains the case labels directly. In contrast to C, the group of statements following a case label have their own lexical scope so that variable declarations may not cross case labels.

HISTORY

• changed (3.2.10) – constrained the grammar to require a block for the switch() body, not just a statement. This differs from the C syntax, but was necessary as the compiler didn’t handle the statement case correctly.
• changed (3.3) – allowed to pass values of the wrong type to switch(), the driver would in that case use the default case. Before, values of the wrong type caused a runtime error.
• changed (3.3.718) – disallowed case labels in inner blocks and variable declarations that cross case labels.

SEE ALSO

for, foreach, do-while, if, while