BASIC9.WPS

BASIC LANGUAGE PROGRAMMING

USING IF THEN/ELSE/ELSEIF/ENDIF

BRANCH INSTRUCTIONS

One of the most powerful features of computers is their

ability to make decisions. This sets them dramatically aside

from calculators. Some of the decisions which a computers can make are:

1) < means less than

2) > means greater than

3) <= means less than or equal to

4) >= means greater than or equal to

5) = means equal to

6) <> means NOT equal to

Here is a simple program which employs IF/THEN branching to

decide if one number is larger than another. PLEASE NOTE THAT THE ELSE STATEMENT REQUIRES NO ARGUMENT AFTER IT. The ELSE branch is taken automatically if the program cannot find a TRUE IF -or- ELSEIF statement.

REM THIS PROGRAM DECIDES WHICH NUMBER IS LARGER

CLS

INPUT A

INPUT B

IF A > B THEN

PRINT "A IS LARGER THAN B"

ELSEIF A = B THEN

PRINT " A IS EQUAL TO B"

ELSE

PRINT " B IS LARGER THAN A"

ENDIF

END

(continued - next page)

More complex decisions can be made by combining IF/THEN/ELSEIF/ELSE decisions with AND or OR statements. Here is an example of a program which assigns letter grades to numerical grades by using the IF/THEN/ELSEIF ELSE AND ENDIF statements:

CLS

INPUT GRADE

IF GRADE >= 80 THEN

PRINT " CONGRATULATIONS YOU HAVE AN -A- IN THE COURSE"

ELSEIF 80> GRADE AND GRADE >=70 THEN

PRINT " CONGRATULATIONS YOU HAVE AN -B- IN THE COURSE"

ELSEIF 70> GRADE AND GRADE >=60 THEN

PRINT " CONGRATULATIONS YOU HAVE AN -C- IN THE COURSE"

ELSEIF 60> GRADE AND GRADE >=50 THEN

PRINT " YOU HAVE A -D- IN THE COURSE"

ELSE

PRINT " CONSIDER A DIFFERENT OCCUPATION -F-"

ENDIF

END

Assignment- Use IF/THEN/ELSEIF AND ENDIF statements to

write the following programs:

1) Write program which asks the student their name and age.

If the student is over 16 years of age, the program is

to then remind them (by name) that they are eligible for

a driving license.

2) Write a program which asks the students for their name,

best subject and average in that subject and then

prints out a statement summarizing that information and

also prints out a letter grade for the subject in the

statement.

3) Write a program which asks the user to guess a number

between 1 and 10 and gives the user hints if he/she

is guessing high or low. This process is to repeat itself

until the person can guess the number correctly

(Hint - using a FOR/NEXT LOOP could help! Consider the

maximum number of wrong guesses a person could make in

setting the loop up. Also consider how to end the loop

prematurely if the user guess the correct answer)

Copyright - Barry Boyle (bboyle@kawartha.net)