C Programming - Expressions - Discussion

Discussion Forum : Expressions - Find Output of Program (Q.No. 6)
6.
What will be the output of the program?
#include<stdio.h>
int main()
{
    int i=4, j=-1, k=0, w, x, y, z;
    w = i || j || k;
    x = i && j && k;
    y = i || j &&k;
    z = i && j || k;
    printf("%d, %d, %d, %d\n", w, x, y, z);
    return 0;
}
1, 1, 1, 1
1, 1, 0, 1
1, 0, 0, 1
1, 0, 1, 1
Answer: Option
Explanation:

Step 1: int i=4, j=-1, k=0, w, x, y, z; here variable i, j, k, w, x, y, z are declared as an integer type and the variable i, j, k are initialized to 4, -1, 0 respectively.

Step 2: w = i || j || k; becomes w = 4 || -1 || 0;. Hence it returns TRUE. So, w=1

Step 3: x = i && j && k; becomes x = 4 && -1 && 0; Hence it returns FALSE. So, x=0

Step 4: y = i || j &&k; becomes y = 4 || -1 && 0; Hence it returns TRUE. So, y=1

Step 5: z = i && j || k; becomes z = 4 && -1 || 0; Hence it returns TRUE. So, z=1.

Step 6: printf("%d, %d, %d, %d\n", w, x, y, z); Hence the output is "1, 0, 1, 1".

Discussion:
51 comments Page 1 of 6.

Suneeta mishra said:   2 years ago
And (&&)operator should be true for all conditions and in OR (||), at least one condition should be true.
(1)

Adi sha said:   3 years ago
Precedence is && then || (Associativity is right to left).

Rutuja said:   3 years ago
Please explain why step 3 is false.

If T && F then it's T or F?
(2)

Anomie said:   4 years ago
@All.

Kindly read below logical operators with examples

&& Logical AND. True only if all operands are true.

If c = 5 and d = 2 then, expression ((c==5) && (d>5)) equals to 0.

|| Logical OR. True only if either one operand is true.
If c = 5 and d = 2 then, expression ((c==5) || (d>5)) equals to 1.

! Logical NOT. True only if the operand is 0

If c = 5 then, expression !(c==5) equals to 0.
(1)

Sahana S Shenoy said:   6 years ago
All the expressions evaluates from left to right(in case of RHS and in case of w=expression, it is right to left that means expression is evaluated first then assigned to w) as the AND has the highest precedence over ||.

--->the number other than "zero" is always "true"

so w=T||T||F----->T||F
w=T
x=T&&T&&F---->T&&F
x=F
y=T||T&&F----->T||F
y=T
z=T&&T||F------>T||F
z=T.
(4)

MAHESH said:   6 years ago
Expressions are evaluated from RIGHT TO LEFT.

Then compute the result.
(1)

Prashant said:   6 years ago
Step 4: y = i || j && k;
In step 4 put expression into brackets like : y = (i || j ) && k which will giev o/p as 0 which mean in real time && has a greater precedence than II so is the answer.

Dipak said:   6 years ago
Binary Number is a combination of 0 and 1.

So in above example, positive(+) numbers are assumed as 1 and negative(-) numbers are assumed as 0.

We all know ANDing operation of two binary digit i.e.

1 1
1 0
-------------
1 0

Note: ANDing means multiplication of binary numbers.


we all know ORing operation of two binary digits i.e.
1 1
1 0
---------------
1 1

Note: ORing means addition of binary numbers.

Sid said:   7 years ago
@Prichita.

X=I && j && k;
So substitute values,
X=4 && -1&&0;
--> here 0 means false ....&& (Anding) any value with 0 become 0 only that is false only.

Prichita said:   7 years ago
How did we get x=0?

Why is it false?


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