Contents Previous Next Subchapters

If Statement
Syntax if logical value then first  statement
if logical value then first statement else second statement
See Also equality , ordered , block , goto

Description
Executes the first statement if the logical value is true, where logical value is a scalar. If the second statement is present and the logical value is false, the second statement is executed.

Tutorial
Because O-Matrix cannot process a line containing a partial statement the following examples cannot be typed at the O> prompt. It can be copied from the help file and pasted to the O> prompt or run from an editor window.

If you enter
     x = 8
     y = 4
     if x / y == 2 then print x, "/", y, "=", x / y
 O-Matrix will respond
     8 / 4 = 2
 The statement following an else clause is executed if logical value is false. If you run the program
     x = 4
     y = 5
     if x > y then z = 0
     else z = 6
     print z
 O-Matrix will respond
     6
 More advanced examples that use the if statement can be found in the Block section of this chapter.

Reference
Directives cannot be used in if statements unless as part of a block. (See the Block section of this chapter for more information.)

For example, if you enter
     if 2 > 1 then const x = 1
 O-Matrix will respond with an error message.

An else clause is grouped with the first preceding if clause that does not yet have an else clause grouped with it. If, from an editor window, you run the program
     if 2 > 1 then if 1 > 2 then z = 1
     else z = 2
     print z
 O-Matrix will respond
     2
 The z = 2 statement was executed because 1 > 2 is false.