Test by Bikram | Mock GATE | Test 1 | Question: 6

Question

What is the output of the following program?
main( )
{
int i=4, z=12;
if( i=5 || z > 50)
printf(“ Gate2017”);
else
printf(“ Gateoverflow”);
}

• A. Gate2017
• B. Gateoverflow
• C. syntax error
• D. Gate2017Gateoverflow

Comments

@BILLY,  i think u r confused with == & =, in assignment if statement proceeds then its true, and short circuiting logic is from OR boolean

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thnk u.... :)

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Main function must always return int value and int is missing as returntype so syntax error.

Answer 1

i=5 will assign value 5 to i so the if statement (i=5||z >50) is true ,  “printf” statement will print Gate2017.

Comments

if(i=5) it is taking true

and printing 1

may be it is the case.not sure

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@ Vijay Thakur,

Uddipto is right, it is taking it as true.

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No... it's not correct !

the condition is :-   i=5 || z>20

as per precedence and associativity rules,

'=' have less priority than || and >

$\color{red}{(}i\color{red}{)} = \color{blue}{(\;\;\;} 5\; ||\; \color{green}{(}z > 20\;\color{green}{)}\;\; \color{blue}{)}$

due to this type of evaluation it assigns the value 1 to i.

(i=5) || z>20  =========> this assigns i = 5

Answer 2

int main()
{
    int i=4 , z = 12;
    if(i = 5 || z > 50)
        printf("Inside if %d",i);
    else 
        printf("Inside else %d",i);
    
}
Output : Inside if 1

This is because of precedence, this expression is evaluated as i = (5||z>50) as 5 is a non zero number so it evaluates as true and printf inside if is executed. 

Logical OR has higher precedence than assignment operation.
Source: http://www.difranco.net/compsci/C_Operator_Precedence_Table.htm

A few variations for more clarity:

int main()
{
    int i=4 , z = 12;
    if(i = 5 && z > 50)
        printf("Inside if %d",i);
    else 
        printf("Inside else %d",i);
    
}

Output : Inside else 0

int main()
{
    int i=4 , z = 12;
    if(i = 0 || z > 50)
        printf("Inside if %d",i);
    else 
        printf("Inside else %d",i);
    
}

Output: Inside else 0

Answer 3

here in if i is assigned 5 any non-zero value is taken as true ,therefore it is true

if(i=5 ||z>50) will become if(5|| z>50) if(true|| z>50)

Gate2017 will be printed