Question

What is the value of x after each of the following statements is encountered in a computer program, if x=1 before the statement is reached? Please, justify your answer.
a) if (1+2=3) then x:=x+1
b) if ((1+1=3) OR (2+2=3)) then x:=x+1
c) if ((2+3=5) AND (3+4=7)) then x:=x+1

Answer 1

Answer:

x=2

x=1

x=2

Explanation:

a)

This if statement if (1+2=3) checks if the addition of two numbers 1 and 2 is true. Here the addition of 1 and 2 is 3 which is true. So the condition becomes true.

Since the condition is true x:=x+1 statement is executed. This statement means that the value of x is incremented by 1.

The value of x was 1 before the if statement is reached. So x:=x+1 statement will add 1 to that value of x.

x:=x+1 means x=x+1 which is x=1+1 So x=2

Hence value of x is 2 (x=2) after the execution of x:=x+1

b)

In statement b the value of x will be 1 because both the mathematical operations in the if statement evaluate to false.

which means in b, x:=x+1 will not be executed and value of x remains unchanged i.e x=1

In (c) the value x will be 2 because the condition in the if statement is true. Both mathematical expressions 2+3=5 and 3+4=7 are true. Therefore x:=x+1 will be executed and value of x will be incremented by 1. Hence x=2