What is output of following program

Question

It is not any gate question but just my doubt over the topic C programming?

Ques:- What will be the output of the following program?

void main(){

      int a=0,x=0;

      a = 10;

      x = ++a + ++a + ++a;

      printf("Value of X = %d and Value of A = %d",x,a);

}

 

What will be the output of the above program?

Please give explanation also for your answer.

(Please tell what was your approach in this answer)

Comments

Sorry to all I was not knowing that this question is a duplicate one.I just randomly created this question.

 

 

Sorry to all.

---

They don't ask these type of question in GATE (undefined behaviour).

---

https://gateoverflow.in/62411/undefined-behaviour-in-c

Answer 1

here a is initialized to 0 and x is initialised to 0.

in the next line value of a becomes 10,

x=++a + ++a + ++a

there will be many answers depends upon order of evaluations so output of program is undefined.

for example one of the answer will be x=36 and a=13 when we go from right to left

when we evaluate the expression after computing final value of a then x=39 and a=13

there might be other answers too so output is undefined

Comments

Hi, Can you please explain me how did you get x=39 and a=13.

I am able to get x = 36 and a = 13 but x=39 I am not able to understand.Please help me out :)

---

finally we got a=13 then x=++a + ++a + ++a =>x=13+13+13 =>39