Mikroelektronika MIKROE-742 데이터 시트

Use the case statement to pass control to a specific program branch, based on a
certain condition. The 

case

statement consists of a selector expression (a condition)

and a list of possible values. The syntax of the 

case

statement is:

case selector of

value_1 : statement_1
...
value_n : statement_n

[

else default_statement]

selector

is an expression which should evaluate as integral value. 

values

can be

literals, constants, or expressions, and 

statements

can be any statements.

The 

else

clause is optional. If using the else branch, note that there should never

be a semicolon before the keyword 

else

.

First, the 

selector

expression (condition) is evaluated. Afterwards the case state-

ment compares it against all available values. If the match is found, the 

statement

following the match evaluates, and the case statement terminates. In case there are
multiple matches, the first matching statement will be executed. If none of values
matches selector, then 

default_statement

in the else clause (if there is some) is

executed.

Here’s a simple example of the case statement:

case operator of

'*' : result := n1 * n2;

'/' : result := n1 / n2;

'+' : result := n1 + n2;
'-' : result := n1 - n2

else result := 0;
end;

Also, you can group values together for a match. Simply separate the items by commas:

case reg of

0:       opmode := 0;

1,2,3,4: opmode := 1;

5,6,7:   opmode := 2;

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 5