Case

Case is used to provide an alternative control structure based on the value of a given expression.

Syntax

 Case EXPRESSIONWhen EXPRESSION_LISTINSTRUCTIONS...When DefaultINSTRUCTIONSEndcase

The When Default is optional; if present, it must be the last When instruction of the Case. The instructions placed after it will be executed only if no matching expression was found in all the When instruction following the Case.

Examples

 # Depending on the value of CHOICE, a particular action will be performed.# If "R" is chosen, nothing is done.Case toupper(CHOICE)When "E","D" : Gosub DELETIONWhen "Q","S" : Goto QUITWhen "R"When "M" : Gosub MODIFICATIONWhen Default : Gosub HELPEndcase# Alternative on the expression date$-NUMBER_OF_DAYS that is compared to# other variables or complex expressions# For all the other cases, as there is no "When Default" instruction, nothing will be executed#Case date$-NUMBER_OF_DAYSWhen [29/05/1959]RESULT="This is my birthday"When [18/06/1944],[08/05/1945],[11/11/1918]RESULT= "This was a historical date"RESULT+=" ("+format$(D:DD[/]MM[ ]4Y",date$-NUMBER_OF_DAYS)+")"When date$RESULT "We are today"Gosub ACTIONS_TODAYEndcase

Description and comments

• Case is used to allow alternatives within a script based on the value of an expression that will be compared to lists of values.
• At most, one alternative is executed (a Case is the same as [If] … [Elsif] … [Else] … [Endif]). If there is no When Default instruction and if no value matches the expression, no instruction in the Case will be executed.
• No instruction can be placed within the Case and the first When (not even a comment).
• When no instructions are found between a When and the next Wheninstruction, no instruction will be executed if the first When matches the Case, unlike languages such as C. In order to execute the same instructions for several values, you have to put them in a list that follows the When instruction.

Errors

See also

When, Endcase, If, Then, Else, Endif.