2. Operators

 

Arithmetic Operators

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int x = -3, y = +4;
    printf("%d %d", x, y);
}

-3 4

2. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 17, b = 4;
    printf("%d\n, a + b);
    printf("%d\n", a - b);
    printf("%d\n", a * b);
    printf("%d\n", a / b);
    printf("%d", a % b);
}

21
13
68
4
1

3. What is the output of the following C code?
#include <stdio.h>
int main()
{
    float a = 12.4, b = 3.8;
    printf("%.2f\n", a + b);
    printf("%.2f\n", a - b);
    printf("%.2f\n", a * b);
    printf("%.2f", a / b);
}

16.20
8.60
47.12
3.26

4. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int x = 9, y = 2;
    float z = 2.0;
    printf("9/2: %f\n", x / y);
    printf("9/2: %d\n", x / y);
    printf("9/2.0: %f", x / z);
}

9/2: 0.000000
9/2: 4
9/2.0: 4.500000

Assignment Operators

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int x, y, z, t;
    x = 5, y = 6, z = x + y * 2, t = x;
    printf("x: %d, y: %d, z: %d, t: %d\n", x, y, z, t);


    x, y, z = 10; // x and y values will not change, only z will be assign by 10
    x = y = z = 10;


    x = x + 5;
    x += 5;


    y *= 5;
    z /= 2;
    t %= 5;


    printf("x: %d, y: %d, z: %d, t: %d", x, y, z, t);
    return 0;
}

x: 5, y: 6, z: 17, t: 5
x: 20, y: 50, z: 5, t: 0

Increment and Decrement Operators

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int x = 8;
    printf("%d ", x);  
    printf("%d ", ++x);
    printf("%d ", x);  
    printf("%d ", --x);
    printf("%d", x);
    return 0;
}

8 9 9 8 8
Explanation: Pre-increment and pre-decrement operators updates the value before executing the whole statement.

2. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int x = 8;
    printf("%d ", x);  
    printf("%d ", x++);
    printf("%d ", x);  
    printf("%d ", x--);
    printf("%d", x);
    return 0;
}

8 8 9 9 8
Explanation: Post-increment and post-decrement operators updates the value after executing the whole statement.

3. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 10;
    int b, c;
    b = ++a; // b will be assigned the incremented value i.e., 11.
    c = a++; // c will be assigned the value of a before incrementing it i.e., 11.
    b--;    
    --c;    
    b -= c;
    printf("%d", b);
    return 0;
}

0

4. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 10;
    int y = (++a) + (--a); // brackets will be evaluated before arithmetic addition
    printf("%d", y);
    return 0;
}

20

5. What is the output of the following C code?
#include <stdio.h>
int main()
{
    printf("%d", printf("DCSharma"));
    return 0;
}

DCSharma8
Explanation: printf() returns the number of characters printed.

6. What is the output of the following C code?
#include <stdio.h>
int f1()
{
    printf("Jetha");
    return 1;
}
int f2()
{
    printf("Babita");
    return 1;
}
int main()
{
    int p = f1() + f2();
    printf("%d", p);
    return 0;
}

JethaBabita2
BabitaJetha2
Explanation: Answer can vary from compiler to compiler, so both the answer can be possible.

NOTE: Among n++ and n = n+1, n++ will be executed faster in old compilers but in new compilers n = n+1 is converted as n++ while compiling, so both will take same execution time.
Among n++ and ++n, ++n is more efficient.

Relational Operators

1. What is the output of the following C code for the following inputs:
1. 1 3
2. 0 3
3. 3 0
#include <stdio.h>
int main()
{
    int a, b;
    scanf("%d%d", &a, &b);
    if (a = b)
    {
        printf("Assignment operator ");
        printf("%d", a = b);
    }
    else
        printf("Else executed");
    return 0;
}
1. Assignment Operator 3
2. Assignment Operator 3
3. Else executed

Explanation: If condition will execute for non-zero values of a, but a is assigned by the value of b, so if statement will execute if value of b is non-zero. Also inside printf value of a will be printed, but before that a will be assigned by the value of b.

2. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 10, b = 20, c = 30;
    if (c > b > a)
        printf("TRUE");
    else
        printf("FALSE");
    return 0;
}

FALSE
Explanation: Comparison will happen from left to right, so 30>20 will return 1 which will be compared with 10 and 1>10 will return 0, hence the overall comparion returns 0.

Logical or Boolean Operator

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 2;
    int p = (2 < 10) && (a = 4);
    printf("a=%d ", a);


    int b = 2;
    p = (2 > 10) && (b = 4);
    printf("b=%d ", b);


    int c = 2, d = 2;
    p = (2 > 10) && (c = 4) && (d = 4);
    printf("c=%d d=%d", a);
    return 0;
}

a=4 b=2 c=2 d=2
Explanation: For AND operator, if any condition from left to right returns 0, then further conditions will not be evaluated.

2. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 2;
    int p = (2 < 10) || (a = 4);
    printf("a=%d ", a);


    int b = 2;
    p = (2 > 10) || (b = 4);
    printf("b=%d ", b);


    int c = 2, d = 2;
    p = (2 > 10) || (c = 4) || (d = 4);
    printf("c=%d d=%d", a);
    return 0;
}

a=2 b=4 c=4 d=2
Explanation: For OR operator, if any condition from left to right returns 1, then further conditions will not be evaluated.

Comma Operator

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a, b, c, res;
    res = (a = 8, b = 7, c = 9, a + b + c);
    printf("Output:%d", res);
    return 0;
}

Output:24
Explanation: The comma operator helps to perform multiple assignments in a single statement and at last rightmost value is assigned to res.

2. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 8, b = 7, temp, x;
    printf("a=%d, b=%d ", a, b);
    x = temp = a, a = b, b = temp;
    printf("x=%d ", x);
    printf("a=%d, b=%d", a, b);
    return 0;
}

a=8, b=7 x=8 a=7, b=8
Explanation: The comma operator helps to perform multiple assignments in a single statement.

Conditional or Ternary Operator

1. Which combination of integer variables x, y and z makes the variable a get the value 4 in the following expression?
a = (x > y) ? ((x > z) ? x : z) : ((y > z) ? y : z);
1. x = 3, y = 4, z = 2
2. x = 6, y = 5, z = 3
3. x = 6, y = 3, z = 5
4. x = 5, y = 4, z = 5

x = 3, y = 4, z = 2
Explanation: Nested if else statement, (y>z)?y:z means if y > z, then return y else return z. Only two options contains 4, and only y has value 4, and y will return only when y is greater than both x and z.

sizeof() Operator

• sizeof() is an operator and not a function.
• sizeof() tells the number of bytes required to store an datatype/variable/constant etc.
• sizeof() is a unary operator as it requires only single parameter as input.
• sizeof() gives machine and compiler dependent results.
• Return type of sizeof() is long unsigned int (%lu).
• Parameter given to sizeof() operator is never evaluated.

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int i = 12;
    int j = sizeof(++i);
    printf("%d %d", i, j);
    return 0;
}

12 4
Explanation: Parameter given to sizeof() operator is never evaluated.

2. What is the output of the following C code?
#include <stdio.h>
int main()
{
    printf("%d", sizeof(printf("Accenture")));
    return 0;
}

4
Explanation: Parameter given to sizeof() operator is never evaluated.

Bitwise Operators

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 20;
    int b = 10;
    int c = a & b;
    int d = a | b;
    int e = a ^ b;
    printf("c=%d d=%d e=%d", c, d, e);
}

c=0 d=30 e=30

Shift Operators

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a = 8 >> 1;
    int b = 8 >> 3;
    int c = 3 << 1;
    int d = 3 << 5;
    int e = 11 >> 2;
    int f = 1 << 5 << 4;
    printf("a=%d b=%d c=%d d=%d e=%d f=%d", a, b, c, d, e, f);
}

a=4 b=1 c=6 d=96 e=2 f=512
Explanation: a << b is calculated as a* 2^b and a >> b is calculated as a/2^b.

Precedence and Associativity

1. What is the output of the following C code?
#include <stdio.h>
int main()
{
    int a, b, c, d, e, f, g, h, k;
    a = 8, b = 4, c = 2, d = 1, e = 5, f = 20;
    printf("%d\n", a + b - (c + d) * 3 % e + f / 9);


    a = 17, b = 5, c = 6, d = 3, e = 5;
    printf("%d\n", a % 6 - b / 2 + (c * d - 5) / e);


    a = 4, b = 5, c = 6, d = 3, e = 5, f = 10;
    printf("%d\n", a * b - c / d < e + f); // 0


    a = 8, b = 5, c = 8, d = 3, e = 65, f = 10, g = 2, h = 5, k = 2;
    printf("%d\n", a - b + c / d == e / f - g + h % k);


    a = 8, b = 3, c = 2, d = 3, e = 2, f = 11;
    printf("%d", a - b || (a - b * c) + d && e - f % 3);
}

10
5
0
1
1