Python - If Statements

Another one of the main uses of programming statements is to execute actions based on conditionals. In this article, we will take a brief look at if statements, and how you can use them.

Let's start with an example. Let's pretend we are writing a program for a movie theatre, and we want to very the price of ticket per a buyer's age. We can use if for this.

price = 18 # The standard price
age = 12 # The age of the buyer

if age < 18:
    price = 10 # Discount if you are under 18

print(price)

Alright! Now, if the person is younger than 18, we change the variable price to $12.

Now, let's introduce the elif statement to add a senior discount.

price = 18 # The standard price
age = 12 # The age of the buyer

if age < 18:
    price = 10 # Discount if you are under 18
elif age > 65:
    price = 8 # Discount if you are over 65

print(price)

Very nice. Now, if the person's age is greater than 65, we discount the price to $8. Let's take a look at another way we can do the above.

price = 18 # The standard price
age = 12 # The age of the buyer

if age < 18:
    price = 10 # Discount if you are under 18
if age > 65:
    price = 8 # Discount if you are over 65

print(price)

Here, we get the same result, but both if statements will be checked. I wanted to show you that you don't always need the elif. There are also some advance reasons you will want to use this technique.

Finally, let's end by looking at the else statement.

price = 18 # The standard price
age = 12 # The age of the buyer

if age < 18:
    price = 10 # Discount if you are under 18
elif age > 65:
    price = 8 # Discount if you are over 65
else:
    print("Sorry, no discount.")

print(price)

When our other conditions are not met, we can use the else statement. Here, we use the statement to tell users that they will not be receiving a discount.

And that's it for this lesson :D.

References

• https://docs.python.org/3/tutorial/controlflow.html#if-statements