Arithmetic, Logical & Boolean Operators (OCR AS Computer Science): Revision Note

Arithmetic Operators

What are arithmetic operators?

• Arithmetic operators are symbols or keywords used to perform mathematical calculations and operations on numerical values

• They allow the computer to perform addition, subtraction, multiplication, division, and more

Addition operator (+)

• The addition operator (+) is used to add numerical values together or concatenate strings:

01 sum = 5 + 3
02 fullName = 'John' + ' ' + 'Doe'

• In this example, the addition operator adds the values 5 and 3, resulting in 8

• It also concatenates the strings 'John', ' ', and 'Doe' to form the full name 'John Doe'

Subtraction operator (-)

• The subtraction operator (-) is used to subtract one numerical value from another:

01 difference = 10 - 4

• In this example, the subtraction operator subtracts the value 4 from 10, resulting in 6

Multiplication operator (*)

• The multiplication operator (*) is used to multiply numerical values together:

01 product = 3 * 5;

• In this example, the multiplication operator multiplies the values 3 and 5, resulting in 15

Exponentiation operator (^)

• The exponentiation operator (^) is used to multiply numerical values by the power of another number:

01 product = 3 ^ 3

• In this example, the exponentiation operator multiplies the value 3 to the power 3 (3*3*3), resulting in 27

The division operator (/)

• The division operator (/) is used to divide one numerical value by another:

01 quotient = 10 / 2

• In this example, the division operator divides the value 10 by 2, resulting in 5

The modulus operator (MOD)

• The modulus operator (MOD) returns the remainder when one numerical value is divided by another:

01 remainder = 10 MOD 3

• In this example, the modulus operator divides the value 10 by 3 and returns the remainder, which is 1. 3 will go into 10 a total of three times and there will be a remainder of 1 

Operator precedence (BIDMAS / BODMAS)

• Arithmetic operators follow the rules of operator precedence, which determine the order in which operators are evaluated. Parentheses () can be used to control the order of evaluation:

01 result = 2 + 3 * 4
02 adjustedResult = (2 + 3) * 4

• In the first example, without parentheses, the multiplication (*) is performed before the addition (+), resulting in 14

• In the second example, with parentheses, the addition is evaluated first, resulting in 5, which is then multiplied by 4, resulting in 20

Logical Operators

What are Logical Operators?

• Logical or comparison operators are symbols or keywords used to compare values and return a boolean result. They allow a comparison of variables, or expressions to determine relationships, equality, or inequality between them.

Equal to (==) operator

• The equal to operator (==) compares two values and returns true if they are equal, and false otherwise 

01 x = 5
02 y = 6
03 print(x == y) 

• In this example, the equal to operator compares the value 5 with the value  6. These are not the same number so false is printed

Not equal to (!=) operator

• The not equal to the operator (!=) compares two values and returns true if they are not equal, and false if they are equal 

01 x = 5
02 y = 7
03 print(x != y)

• In this example, the not equal to operator compares the value 5 with the value 7. As they're not equal, true is printed

Greater than (>) and less than (<) operators

• The greater than operator (>) compares two values and returns true if the left operand is greater than the right operand. The less than operator (<) returns true if the left operand is less than the right operand

01 x = 5
02 y = 10
03 print(x > y)
04 print(x < y)

• In this example, the greater than operator compares the value 5 with the value 10, resulting in false

• The less than operator compares 5 with 10, resulting in true

Greater than or equal to (>=) and less than or equal to (<=) operators

• The greater than or equal to operator (>=) compares two values and returns true if the left operand is greater than or equal to the right operand. The less than or equal to operator (<=) returns true if the left operand is less than or equal to the right operand:

01 x = 5
02 y = 10
03 print(x >= y)
04 print(x <= y)

• In this example, the greater than or equal operator compares 5 with 10, resulting in false

• The less than or equal to operator compares 5 with 10, resulting in true

Boolean Operators

What are Boolean Operators?

• Boolean operators are symbols or keywords used to combine and manipulate boolean values. They allow the computer to perform logical operations, such as combining conditions, negating values, and determining whether an expression is true or false.

AND operator

• The AND operator returns true if both operands are true, otherwise returns false:

01 x = 5
02 y = 10
03 z = 15
04 result = (x < y) AND (y < z)

• In this example, the expression (x < y) AND (y < z) evaluates to true because both conditions are true. If any of the conditions were false, the result would be false

OR operator

• The OR operator returns true if at least one of the operands is true, and false if both operands are false:

01 a = 5
02 b = 10
03 c = 15
04 result = (a > b) OR (b < c)

• In this example, the expression (a > b) OR (b < c) evaluates to true because the second condition is true, even though the first condition is false. If both conditions were false, the result would be false

NOT operator

• The NOT operator is used to negate a Boolean value. It returns true if the operand is false, and false if the operand is true:

01 value = false
02 result = NOT value

• In this example, the not operator negates the value of false, resulting in true