case selection statement

Syntax A caseStatement is:
case expn of
{ label compileTimeExpn {, compileTimeExpn } :
statementsAndDeclarations }
[ label :
statementsAndDeclarations ]
end case



Description A case statement is used to choose among a set of statements (and declarations). One set is chosen and executed and then execution continues just beyond end case.
The expression (expn) following the keyword case is evaluated and used to select one of the alternatives (sets of declarations and statements) for execution. The selected alternative is the one having a label value equaling the case expression. If none are equal and there is a final label with no expression, that alternative is selected.


Example Output a message based on value of mark.

case mark of
label 9, 10 : put "Excellent"
label 7, 8 : put "Good"
label 6 : put "Fair"
label : put "Poor"
end case

Example Output a message based on value of name.

case name of
label "horse", "cow" : put "Farm animal"
label "tiger", "lion" : put "Jungle animal"
label "cat", "dog" : put "Pet"
label : put "Unknown animal"
end case

Details The case expression is required to match one of the labels. If it does not, there must be a final label with no expression. Label expressions must have values known at compile time. All label values must be distinct. The case expression and the label values must have the same equivalent type, which must be an integer, char, boolean, an enum type or strings.
Note that there is no way to express a range of values (for example from 5 to 10) in a label. Each individual value must be expressed in the label.