Elementary Statistics and Computer Application

The IF Statement

This statement helps in transferring the control of program execution from one part of the program to another depending on some test-condition.
There are two types

• IF-THEN statement
• IF-THEN-ELSE statement
IF-THEN statement
Its format is



where
n – is the statement number
test-condition – may be relational or logical expression.

When the IF-THEN statement is executed in a program, the test-condition is tested. If the test-condition is true, control of program execution is transferred to statement labeled n. If the test-condition is False, the statement immediately following the IF-THEN statement is executed.
Eg :
5 IF A>10 THEN 125
Program
Given a set of 6 values as -5, 2, 6, -1.1, 0, 4
Develop a program that computes the sum of the values greater than zero.
10 DATA -5, 2, 6, -1.1, 0, 4
20 LET N=0
25 LET S=0
30 READ A
40 LET N = N+1
50 IF A<=0 THEN 70
60 LET S=S+A
70 IF N<6 THEN 30
80 PRINT “SUM=”;S
90 STOP
100 END
Output
SUM=12
2) IF-THEN-ELSE statement
This is more general form of IF statement.
Its syntax is

where
n1 and n2 are labels of other statements.
When the test-condition is true, statement labeled n1is executed. However when the test-condition is false, statement n2 is executed.
Eg:
60 IF A<> B THEN 100 ELSE 200