Notes

Arithmetic and Comparison

Arithmetic

• Addition: a + b
• Subtraction: a - b
• Multiplication: a*b
• Division: a/b
• Remainder / Modulus: a%b

Multiplication can easily run out of the bounds of the given datatype. So take care while multiplying numbers.

Division by zero mostly leads to a fatal error. So take care of b being 0 explicitly.

Remainder can be negative too if you use the modulus operator. SO take care when you need the remainders according to mathematical logic.

Syntactic sugar for assignment: c += 3; and similar for other arithmetic operations as well.

An easy method to reverse a number:

int rev_num(int num){
    int revnum = 0;
    while (num != 0){
        revnum = revnum*10 + num%10;
        num = num/10;
    }
}

Logical Operators

&& logical and

|| logical or

! logical not

Bit operators

• & : bitwise and, take the logical and of each bit of the number.

• | : bitwise or, take the logical or of each bit of the number.

• ^ : bitwise xor, take the logical xor of each bit of the number.

• x << y : shift the bits of x y bits to to the left. Equivalent to multiplication by 2.

• x >> y : same as above except it shifts to the right. Equivalent to floor division by 2.

Bit operators are extremely fast. If possible, prefer using them over other arithmetic operators.

An easy method to swap two numbers without additional variables:

#define swap (x, y) {x = x^y; y = x^y; x = x^y};

Increment and Decrement Operators

Comparison Operators