Relational operators check the relationship between two operands. They return true if the comparison or relation is true otherwise it will return false.
There are six comparison operators in the Python programming language. They are:
Equal To
Not Equal To
Greater Than
Less Than
Greater Than or Equal To
Less Than or Equal To
Equal To (==)
The equal to operator is represented by the double equal sign (==) in the Python programming language. The single equal sign (=) is used for assignment in the Python programming language.
The equal to symbol checks if two operands are equal.
Not Equal To (!=)
This is the opposite of the equal to symbol. It checks if the two operands are not equal.
Greater Than (>)
This checks if the left operand is greater than the right operand.
Less Than (<)
The less than operator is the opposite of the greater than operator. It checks if the operand on the left is less than the operand on the right.
Greater Than or Equal To (>=)
Checks if the left hand operand is either greater or equal to the right hand operand.
Less Than or Equal To (<=)
Checks if the left hand operand is either less or equal to the right hand operand.
Relational operators allow the programmer to define conditions in their code based on the relationship between two variables.
The default mode of execution of a program is from top to bottom. However in the course of the execution of a program, the Python interpreter comes across some statements that change the default mode of execution.
Such statements are called a branch. A branch is an instruction in a computer program that causes a computer to begin executing a different instruction sequence and thus deviate from its default behaviour of executing instructions in order.
Branching is implemented as a series of control statements in high level programming languages. In the Python programming language, these include:
IF Statement
WHILE Loop
FOR Loop
IF Statement
If-Then-Else flow diagram
The IF Statement works by evaluating a programmer specified boolean condition and checking if it evaluates to true or false.
If the condition evaluates to true, certain actions are carried out. An evaluation to false means that alternate actions are carried out.
WHILE Loop
While loop flow diagram
A loop ensures that code is repeated. However in programming when you want ensure that you loop an infinite number of times, you use a WHILE loop.
The WHILE loop consists of a block of code and a condition/expression. The condition/expression is evaluated, and if the condition/expression is true, the code within all of their following in the block is executed. This repeats until the condition/expression becomes false.
In the Python programming language, the WHILE loop has an ELSE branch just like the IF statement.
FOR Loop
For loop flow diagram
When you want to loop a fixed number of times in the Python programming language, you use a FOR loop.
A FOR loop has two parts: a header specifying the iteration, and a body which is executed once per iteration. The header often declares an explicit loop counter or loop variable, which allows the body to know which iteration is being executed. FOR loops are typically used when the number of iterations is known before entering the loop.
Conclusion
Branching statements allow the flow of execution to jump to a different part of the program.
Mastering them is important in the journey of learning how to program.
Euclid’s Algorithm allows you to find the HCF of two numbers. The steps of the algorithm are given below:
Ask the user for 2 numbers
Test which one is bigger
Make the bigger number m and the smaller number n
Set r to be the remainder when m is divided by n
Set n to m
Set r to n
If r is 0, the HCF is n. Stop
Else go back to step 5
This article will cover steps 1 to 3. The first step is to create a script and name it euclid.py.
To write the code for step 1, enter the code shown below into the script:
# Ask the user for the first number
first_number = int(input("Please enter the first number: "))
# Ask the user for the second number
second_number = int(input("Please enter the second number: "))
To test which of the input numbers is bigger, we will use the greater than symbol. We will ignore other cases. The code to do this is shown below:
# Test if the second number is bigger than the first number
if (second_number > first_number):
# Swap if the first number is greater than the second number
temp = second_number
second_number = first_number
first_number = temp
# Print out to check the swap
print(first_number, second_number)
Now the program can receive input and swap them correctly. Below is an image of a running program.
