Question { Infosys, 62545 }

what is the value of b
if a=5;
b=++a + ++a

Answer

The output will be 14.
i.e. The the value of b is 14.
Explanation:
Consider Expression (b = ++a + ++a;)
Initially the value of a is 5. After the first pre increment operator it will be 6 and after second one it becomes 7. So we guess the expression evaluated as (b = 6 + 7 i.e. b = 13). But wait... In C Programming Language ++a is nothing but a = a + 1, am I right? Ofcourse it's right. Now consider the presedense of pre increment operator over addition operator, Compiler first's evaluate both ++a and the perform addition. So first ++a evaluated to 6 i.e. Now a = 6 then second ++a evaluated as 7 i.e. Now a = 7 and overwrite the old value of a. So compiler evaluated our expression as
b = (a = a +1) + (a = a+1); first compiler assign a = 6 and then a = 7 so our expression becomes b = 7 + 7 as same variable can't holds two different values at a time. And finally our main out will be 14.
I hope now you understand it.
Thnk you!