| if | statement |
| Syntax | An ifStatement is:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Description | An if statement is used to choose among a set of statements (and declarations). One set (at most) is chosen and executed and then execution continues just beyond end if. The expressions (the trueFalseExpressions) following the keyword if and each elsif are checked one after the other until one of them is found to be true, in which case the statements (and declarations) following the corresponding then are executed. If none of these expressions evaluates to true, the statements following else are executed. If no else is present and none of the expressions are true, no statements are executed and execution continues following the end if.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Example | Output a message based on value of mark.
if mark >= 50 then
put "You pass"
else
put "You fail"
end if
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Example | Output A, B, C, D or F depending on mark.
if mark >= 80 then
put "A"
elsif mark >= 70 then
put "B"
elsif mark >= 60 then
put "C"
elsif mark >= 50 then
put "D"
else
put "F"
end if
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Example | If x is negative, change its sign.
if x < 0 then
x := - x
end if
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Example | If x is less than zero or greater than maxx, put a message.
if x < 0 or x > maxx then
put "Out of bounds!"
end if
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Example | If the boolean flag is true and name is “stop”, put a message and return.
if flag and name = "stop" then
put "Exiting routine"
return
end if
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Details | Several statements and declarations can appear after a particular then.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| See also | case statements for another way to select among statements.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||