IF...THEN statement

The IF... THEN statement allows us to make a decision regarding program flow based on the result returned by an expression.

Syntax

LN IF expression [,] THEN statement[,]

Points to remember

• If the result of expression is true (or non zero), THEN then statement is executed.
• If the result of the expression is false (or zero), the THEN statement is ignored and execution continues with the next executable statement.
• A comma is allowed before THEN

CS 7.5 Display on the screen for IF..THEN statement

Use of IF..THEN statement in the program.

1. To check the number for given data and print error message. 

Minimum and maximum value data are 10 and 100 respectively.

Ok

LIST

10    REM Learning the use of IF...THEN statement

30    INPUT A

40    IF A<10 THEN PRINT "DATA BELOW THE RANGE"

45    IF A>=10 AND A<=100 THEN PRINT "DATA WITHIN THE RANGE"

50    IF A>100 THEN PRINT "DATA ABOVE THE RANGE"

60    IF A<>0 THEN 30

70    END

Ok

RUN

?  5

DATA BELOW THE RANGE

? 10

DATA WITHIN THE RANGE

? 35

DATA WITHIN THE RANGE

? 150

DATA ABOVE THE RANGE

? 0

DATA BELOW THE RANGE

Ok  

2.CS 7.6 Display on the screen for IF...THEN statement

Ok

LIST 

20   REM To find the largest number among X.Y and Z

30  INPUT " ENTER THE FIRST NUMBER = "; X

40  INPUT " ENTER THE SECOND NUMBER = ";Y

50  INPUT " ENTER THE THIRD NUMBER = ";Z

60  IF X>Y THEN GOTO 100

70  IF Y>Z THEN GOTO 110

80  PRINT " THE LARGEST NUMBER IS "; Z

90 GOTO 140

100 IF X>Z THEN GOTO 130

105 GOTO 80

110 PRINT " THE LARGEST NUMBER IS " ; Y

120 GOTO 140

130 PRINT " THE LARGEST NUMBER IS " ; X

140 END

Ok

RUN

ENTER THE FIRST NUMBER = ? 68

ENTER THE SECOND NUMBER = ? 139

ENTER THE THIRD NUMBER = ? 23

THE LARGEST NUMBER IS 139