If else statement in Python
problem
You’re learning Python and you came across the idea of control flow that can happen using the if statement. In Python if we wish to change the course of actions by checking for a logical condition we use this mechanism. In this post we will see a simple example that given the user’s age it prints if they are adult or not.
SOLUTION
Let’s suppose we have a program that reads from the user their age and prints to the output if they’re adult or not.
To read from the user’s console we use the input() function as follows:
age = int(input (“Please enter your age: ”))
The age variable holds the number entered by the user. We also used the int() function that converts a number from a string to an integer. For example “18” to 18 so we can deal with it in numerical fashion
if statement
Next, let’s add the if condition:
if age >= 18: #check if they’re adult
print(“You’re adult”)
else:
print(“Not adult”)
print(“End”)
The if statement above accepts a boolean expression (age >=18) and based on that the program flow moves accordingly. If the expression “age >= 18” returns True, then it prints “You’re adult” and then it prints “End”.
If it’s False it goes to the else section and prints the “Not adult” message followed by “End”.
Hence we call it control flow. The program tends to flow in successive order, meaning that it will be executing commands one after the other one; line by line.
The if statement changes that. In the above code snippet, it goes to line 1 and then either at line 2 or at line 4 and then at line 5.
Also, other mechanisms change the flow like a for-loop.
running
python3 if_else.py
output
> With input 18
> With input 17
conclusion
In this post we saw how to use a very simple if – else statement in python and how the flow of a program changes based on a logical condition (boolean expression).
Share it!
Ellion
Professional IT consultant, writer, programmer enthusiast interested in all sorts of coding.
Eats all cookies 🍪