Output of C programs | Set 55 (Ternary Operators)

Predict the output of below programs
Question 1

#include <stdio.h>
int main()
{
    int x, a = 0;
    x = sizeof(a++) ? printf("Geeks for Geeks\n") : 0;
    printf("Value of x:%d\n", x);
    printf("Value of a:%d", a);
    return 0;
}

Output:

Geeks for Geeks
Value of x:16
Value of a:0

Explanation: sizeof is a compile-time operator, so at the time of compilation sizeof and its operand get replaced by the result value. The operand is not evaluated (except when it is a variable length array) at all; only the type of the result matters. In sizeof operator, a++ will not evaluated. So it will remain same i.e. value of a will be 0.
printf returns the number of width. Geeks for Geeks is of 16 width. This will return 16.So x is now 16.

Question 2

#include <stdio.h>
int main()
{
    int x;
    x = 5 > 8 ? 10 : 1 != 2 < 5 ? 20 : 30;
    printf("Value of x:%d", x);
    return 0;
}

Output:

Value of x:30

Explanation:

exp1?exp2:exp3          
5 > 8 ? 10: 1!= 2<5 ? 20:30

Output of exp1 is false, so exp3 (1 != 2 <5 ? 20 : 30) will be evaluated. In exp3, this is also form of ternary operator.
1 != 2< 5 ? 20 : 30 (exp1 ? exp2 : exp3)
Now, exp1 will be evaluated. According to operator precedence, 2<5 will be evaluated first (will give output 1). Now, exp1 is like 1!=1 (condition is false). So, exp3 will be evaluated. Therefore, final output is 30.


Question 3

#include <stdio.h>
int main()
{
    int x;
    x = 5 < 8 ? 1 != 2 < 5 == 0 ? 10 : 20 : 30;
    printf("Value of x:%d", x);
    return 0;
}

Output:

Value of x:10

Explanation :

exp1?exp2:exp3
5 < 8? 1!=2<5 == 0 ? 10:20:30

exp1 is true, so exp2 will be evaluated. exp2 is also in form of ternary operator.
1!= 2<5 == 0? 10 : 20 (exp1?exp2:exp3)
exp1(1 != 2 < 5 ==0)is evaluated. In exp1, according to operator precedence, 2<5 will be evaluated first(condition is true). Now exp1 is 1!=1==0. Again, according to operator precedence, 1==0 is evaluated(condition is false). Now exp1 is 1!=0(condition is true). Now, exp2 will be evaluated. Therefore, final output is 10.


Question 4

#include <stdio.h>
#include <stdio.h>
int main()
{
    int x;
    x = 2 > 5 != 1 ? 5 < 8 && 8 > 2 ? !5 ? 10 : 20 : 30 : 40;
    printf("Value of x:%d", x);
    return 0;
}

Output:

Value of x:20

Explanation:

exp1?exp2:exp3
2 > 5 != 1 ? 5 2 ? !5 ? 10:20:30:40

exp1 will be evaluated always. According to operator precedence, 2>5 will be evaluated first(condition is false). Now, exp1 is 0!=1.Condition is true.So, exp2 will be evaluated, this is also in ternary operator form.

52 ? !5 ? 10:20:30 
(exp1?exp2:exp3)

exp1 will be evaluated. According to operator precedence, 52 will be evaluated(condition is true). Now, exp1 is 1&&1(condition is true). So exp2 will be evaluated, it is also in form of ternary operator.

!5 ? 10:20 (exp1?exp2:exp3)

exp1 will be evaluated, value of !5 is zero, so exp3 will be evaluated.Final output will be 20.


Question 5

#include <stdio.h>
int main()
{
    int x;
    x = 2 > 5 ? 1 != 2 > 5 ? 10 : 20 : 5 < 8 ? 2 != 2 > 5 ?
    !5 ? 30 : !1 != 1 ? 40 : 50 : 60 : 70;
    printf("Value of x:%d", x);
    return 0;
}

Output:

Value of x:40

Explanation

exp1?exp2:exp3
2>5   ?   1!=2>5?10:20   :  55?!5?30:!1!=1?40:50:60:70;

exp1 will be evaluated always.2>5(condition is false), so exp3 will be evaluated, which is also in form of ternary operator.

55?!5?30:!1!=1?40:50:60 : 70  (exp1?exp2:exp3)

exp1 will be evaluated, 5<8(condition is true), so exp2 will be evaluated, which is also in form of ternary operator.

2!=2>5  ?  !5?30:!1!=1?40:50  :  60 (exp1?exp2:exp3)

exp1 will be evaluated.According to operator precedence, 2>5 will be evaluated first(condition is false). So, exp1 is now 2!=0(condition is true). Now, exp2 will be evaluated, which is in form of ternary operator.

!5  ?  30  :  !1!=1?40:50  (exp1?exp2:exp3)

exp1 will be evaluated, value of !5 is zero. So, exp3 will be evaluated, which is in form of ternary operator.

!1!=1  ?  40  :  50  (exp1?exp2:exp3)

exp1 will be evaluated.According to operator precedence, !1 will be evaluated first ie. 0.Now, exp1 is 0!=1(condition is true), exp2 will be evaluated. Therefore final output is 40.

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