switch Statement

switch Statement

The switch statement lets you write an if ... else if chain more concisely. It has the following syntax.

switch(base_expression)
{
**case** condition_expression1 :

case condition_expression2 :

:
:

**default**:

:
:
}

base_expression is an expression, and it is evaluated first. Each condition_expression? following a case inside the block after switch is also an expression.

The condition_expression? entries are evaluated one after another within the block. When a result equals base_expression, execution starts from there. Statements written before a matching condition_expression? are skipped. Once a match is found, subsequent case and default labels are ignored.

default: can be omitted. If default is present, the statements following default are executed when none of the condition_expression? entries match.

To leave the block, write break;. Forgetting break and running on into the next case is a common mistake, so be careful.

    switch(a)
    {
    case 0:
        inform("a is 0");
        break;
    case 1:
        inform("a is 1");
        break;
    case 2:
        inform("a is 2");
        break;
    default:
        inform("a is neither 0, 1 nor 2");
    }


    switch(a)
    {
    case 0:
    case 1: // no break, so case 0 falls through to here
        inform("a is 0 or 1");
        break;
    case 2:
        inform("a is 2");
    } // no default, so nothing is executed for values other than 0, 1 and 2


    switch(a)
    {
    case b+1: // an expression can follow case
        inform("a==b+1");
        break;
    case c+b:
        inform("a==c+b");
    }

    switch(str)
    {
    case "aiueo": // strings can be used too
        type=1;
        break;
    case "kakikukeko":
        type=2;
        break;
    }