Python OR Operator

Logical OR

Programming is a mixture of mathematics, logic, and many more domains. To solve any problem in mathematics, from textbook to real-time, we need addition, subtraction, multiplication and division operators. These are the fundamental operators needed in mathematics. In similar way, to perform any operation on variables or values, Python has 7 types of operators, and each is useful. Among these, "OR" is one of the operators in Python, and it belongs to Logical operators.

Logical operators mainly deal with decision-making needs. There are three operators under logical operators:

Logical AND
Logical OR
Logical XOR

This article discusses the OR operator with examples for a clear understanding.

Basic:

In languages like C and Java, "||" represents the OR operator, but in Python, we say "or" without using any special symbol.

Syntax: a or b

Return value: This operator either returns "True" or "False", depending on the operands.

If both the operands/expressions on either side of the operator are false, it returns False.
If at least one of the operands is true or if both are true, it returns True.

Truth tale for "OR" Operator:

Expression 1	Expression 2	(Expression 1 and Expression 2) returns:
True	True	True
True	False	True
False	True	True
False	False	False

Need for OR operator:

Suppose we need a number; if it is positive, it has to be greater than 20; if it is negative, it has to be less than -20. To meet these conditions, if we write the code using conditional statements:

num = int (input ("Enter a number: "))
if (num < -20):
    print ("True")
elif (num > 20):
    print ("True")
else:
    print ("False")

Output:

Understanding:

In the above code,

First, we check if the number is negative and less than -20. If it is true, one condition is true, then we don't need to check the next condition, so we print "True".
If it is not true, then the elif block will be executed, checking if the number is positive and greater than 20. If this condition is true, then it prints "True".
If both if and elif are false, then else block will be executed to print "False".

Writing the above code using just the "OR" operator:
1. We can check both the conditions at one go in one line.
2. If at least one condition is true, it immediately returns "True".
3. If both the conditions are false, it returns "False".

num = int (input ("Enter a number: "))
if (num < -20 or num > 20):
    print ("True")
else:
    print ("False")

Output:

Using "or" makes the code simple, readable, and decreases the length of the code.

Let us take another example with a real-time application:

Suppose you are organizing a coding competition for b-tech and m-tech students; for any student to take part, he should either be a b-tech or an m-tech student. Any person who is neither a b.tech or m.tech student is not allowed to enter the competition. So, we need to check if at least one condition is true.

Code:

name = input ("Please enter the participant's name: ")
course = input ("Please enter the course the participant's studying\nPlease   	 		        enter the name of the course in capital letters without spaces 			        or other characters in between like BTECH and MTECH: ")
if (course == "BTECH" or course == "MTECH"):
    print ("Congratulations!, You are eligible for the competition")
else:
    print ("Only students in B-Tech and M-Tech are allowed to the competition. 	  	    Sorry! We can't enroll you in")

Output:

"or" with just two numbers:

Let us now see what happens if we give two decimal integers on both sides of the "or" operator:

Pre-requisite: Generally, "or" checks if at least one operand is True. Any number greater than 0 represents True, and 0 represents False.

num1 = int (input ("Enter a number: "))
num2 = int (input ("Enter another number: "))
print (num1 or num2)

Sample outputs:

Understanding:

In the first case:
- Both the numbers are greater than the 0 - True or True condition. Hence, "or" returns True.
- The condition of "or" is that at least one operand must be True. Hence, after confirming that the first number- 4 (>0) is true, without checking the second number, it returned "True" with the first number.
In the second case:
- The first number is 0-False; "or" checks the second number, which is 1 (>0) - False or True condition. Returns
In the third case:
- The first number is 0-False; "or" checks the second number, which is 0 again - False or False. Returns False.

The "or" operator searches the operands to find a "True". Once it finds a "True", it immediately returns True without checking the rest of the operands. This condition is called "The short circuit" or "Lazy evaluation."

"or" with multiple operands:

num1 = int (input ("Enter the first value: "))
num2 = int (input ("Enter the second value: "))
num3 = int (input ("Enter the third value: "))
print (num1 or num2 or num3)

Sample outputs:

Understanding:

It is the same as having two operands. "or" checks for a "True", and if it finds one, it returns "True", and if it doesn't find at least one True, it returns "False".

Bitwise OR (|):

There is another "or" operator in Python. It is a bitwise operator. We represent it as "|". Both are called "or" operators. Now, let us see the difference between the two operators:

Binary language is the language of a computer. All the inner mechanisms happen concerning bits. Bitwise operators are the set of operators that allow the programmer to perform bitwise operations on integers. There are six bitwise operators:

Bitwise AND
Bitwise OR
Bitwise NOT
Bitwise XOR
Bitwise right shift
Bitwise left shift

The difference between (logical or, bitwise or), (logical and, bitwise and), (logical not, bitwise not) lies in their names.

If we use any bitwise operator, first, the integer is converted into binary bits, and then the operator will perform the operation bit-by-bit.
Here, 1 represents True, and 0 represents False.
After the operation, the binary number will be converted to decimal and returned as the output.

The operation of bitwise or:

The given integers are converted into bits (binary), and The operator will operate on every corresponding bit of the two numbers.

Bit 1 (operand 1)	Bit 2 (operand 2)	Return value
0	0	0
1	0	1
1	1	1
0	1	1

Let us take an example:

If num1 = 3 and num2 = 4:

3 -> 011

4 -> 100

Performing |:

If we perform logical or on 3 and 4, we'll get True and 3 will be returned:

num1= int (input ("Enter a number: "))
num2 = int (input ("Enter another number: "))
print (num1 or num2)
print (num1 | num2)

Output:

These are the two "or" operators available to use in Python language.

Logical OR vs Bitwise OR:

Logical or	Bitwise or
Logical or is represented by "or."	Bitwise or is represented by "\|."
It is defined only for Boolean values; even if we use expressions, they will be evaluated as True or False.	It is defined for integer values as well as Boolean values Print (True \| False) -> True
It searches for a True value, and if it finds one, it doesn't evaluate the rest of the expression and returns "True". This phenomenon is called "Lazy evaluation".	Even if the operator finds a True value, it continues evaluating the rest expressions.
This operator is mostly used for decision-making and truth testing.	Bitwise operators are designed for lower-level bit manipulations.
Every number greater than 0 evaluated as "True" and every number == 0 or < 0 is evaluated as "False"	1 represents "True", and 0 represents "False".
In the operator hierarchy, Bitwise operators have higher precedence than the logical operators.