C Programming - C Preprocessor - Discussion

15. 

What will be the output of the program?

#include<stdio.h>
#define MAX(a, b, c) (a>b ? a>c ? a : c: b>c ? b : c)

int main()
{
    int x;
    x = MAX(3+2, 2+7, 3+7);
    printf("%d\n", x);
    return 0;
}

[A]. 5
[B]. 9
[C]. 10
[D]. 3+7

Answer: Option C

Explanation:

The macro MAX(a, b, c) (a>b ? a>c ? a : c: b>c ? b : c) returns the biggest of given three numbers.

Step 1: int x; The variable x is declared as an integer type.

Step 2: x = MAX(3+2, 2+7, 3+7); becomes,

=> x = (3+2 >2+7 ? 3+2 > 3+7 ? 3+2 : 3+7: 2+7 > 3+7 ? 2+7 : 3+7)

=> x = (5 >9 ? (5 > 10 ? 5 : 10): (9 > 10 ? 9 : 10) )

=> x = (5 >9 ? (10): (10) )

=> x = 10

Step 3: printf("%d\n", x); It prints the value of 'x'.

Hence the output of the program is "10".


Nandu said: (Jan 7, 2012)  
I can't understand the step two, the statement "(5>10?:10)" has become (10).

How is it possible?

Abhimanyu said: (Jul 15, 2013)  
@Nandu.

The statement will the pointer will not go to the true section of ternary operator in case of (5>9) So the the pointer will go in (9>10) and again in false section and answer will be 10.

Monika said: (Jul 17, 2014)  
We have evaluate from the right side, (a>b?a:b) if the condition is true then it will take the value of a or else it will take b value.

Here, 9>10 is wrong so its takes the value 10. Then 5>10 is also wrong So again it takes the value 10.

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