ISRO-2013-63

Question

Consider the following $C$ code.

#include <stdio.h> 
#include <math.h> 
void main ()  
{  
      double pi = 3.1415926535;   
      int a = 1;  
      int i;    
      for (i=0; i < 3; i++) 
            if (a = cos(pi * i/2)) 
                  printf("% d", 1);  
            else printf("%d", 0); 
}

What would the program print?

• A. $000$
• B. $010$
• C. $101$
• D. $111$

Comments

@makhdoom, Is there any typo, I mean check the condition in if. It is single = or double ==. Verify this?

Answer 1

Initially I thought there is a typo in this line

if (a = cos(pi * i/2))

Then I checked the ISRO paper and found that it is correct i.e. @makhdoom has not done any mistake.

According to that,

i = 0  : Cos(0), i.e. a = 1 i.e. condition will be True, hence it will print 1.

i = 1  : Cos(Pi/2) i.e. a = 0 i.e. Condition will be False, Hence It will print 0.

i = 2  : Cos(Pi) i.e. a = -1, i.e. Condition will be True, Hence It will print 1.

Hence answer is C. 101

Comments

When I=2 than how 3.1*I/2=-1 give some explanation

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yess true because for assignment operation value  will be assigned and will enter into if loop every time hence ans should be D)111

you can check this : https://www.sololearn.com/Discuss/1374478/can-we-put-assignment-operator-in-if-condition

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can anyone explain how cos(Pi) = -1 ?

Answer 2

for i=0  

if(a=cos0)  that means  if(1) which means true . //here a is use for assignment. and on the basis of assigning value of a if condition is checked

then print 1

then for i=1

if(a=cos(pi/2) that means if(0) which is false then print 0 bcz it is treat as if(a) here a is 0

then for i=2

if(a=cos(pi)) that means if(-1) which is true then print 1  same thing hereit is treat as if(a) here a is -1

so answer is 101

Comments

@srestha and @rude  

o shit!!  i forget to change it .so its blunder now see the solution yr

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ya Now done :)

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I think printf() stmt also wrong.if we want to print 0 and 1 wats the need of use %d. 0 and 1 are not variables.

Answer 3

I am answering through elimination technique

cos(pi*0/2)=cos(0)=1

if(a=1) prints 1 //if(a=0) then only will not enter if condition else it enters//

so a and b options are eliminated.

cos(pi/2) surely not 1 (because cos 0=1 )

so answer is c

comments are welcome!!!

Answer 4

Quoting C11 Assignment operators

An assignment operator stores a value in the object designated by the left operand. An assignment expression has the value of the left operand after the assignment,¹¹¹⁾ but is not an lvalue.

therefore, answer is d 111.

but, anyway i am not 100% sure. stackoverflow is also supporting option d.