Editing FOCAL (programming language) (section)

====IF====
The {{code|IF}} command (abbreviation I) provides a conditional branch based on the sign of the expression. After the numeric expression, the IF command can take one to three line numbers. If the expression is less than zero, execution branches to the first line number;  if equal to zero, to the second line number;  if greater than zero, to the third line number. The language lacked relative operators such as greater than, equal or less than. To branch if X > 5, one must compare X - 5.{{sfn|Manual|1968|p=3.5}}
 02.20 IF (25-25) 2.4,2.3,2.4
 03.01 IF (X) 3.1,3.02,3.1

IF could be short-formed by placing a semicolon (or end of line) beyond the first line number. For example:

 02.20 IF (X)1.8; TYPE "Q"
 02.30 IF (X)1.8,2.50
 02.40 TYPE "P"

In this case the test at 2.20 will cause the program to jump to line 1.8 if the test is negative, otherwise it will continue and type "Q" to the console. Line 2.30 will jump to 1.8 or 2.5 if the value is negative or zero, and otherwise continue to type "P" to the console.{{sfn|Manual|1968|p=3.5}}