Lecture 6 – If Statements – Python Crash Course for Beginners

Welcome to the sixth lecture in this series. Now we are getting deep into programming and we will learn the use of “if statements” in Python.

“if statements” are extremely important in programming as they allow us to build programs that can make decisions based on some condition.

If Statement

“If statement” is used to execute a program based on several decisions. For example, read this:

“If its hot,

It’s a hot day

Drink plenty of water

Otherwise, if it’s cold

Its a cold day

wear warm clothes

Otherwise, it’s a lovely day”

In the above statements, we are making some decisions based on some conditions. The first statement is a condition, the second one is its implication and the third one is executing a decision.

The if statements work similarly.

Let’s look at it in programming.

We are introducing a boolean variable.

is_hot = true

Now we will add an “if statement”

if is_hot:

print("It's a hot day.")

Now this expression will be executed if the above condition is true. To come out of an “if statement” you would have to press “Shift + Tab” to get your cursor in line for a new line of code.

Now, let’s run this program.

Now let’s play with this program.

See what happens if I turn the above condition to false.

It is clear that if the condition is false, the “if statement” is not executed. Now we are going to add a second condition that will be executed if the first condition is not fulfilled.

is_hot = False

if is_hot:

print("It's a hot day.")

print("Drink plenty of water")

else:

print("It's a cold day.")

print("Wear warm clothes.")

print("Enjoy your day")

The “if” condition is false thus the interpreter will go to the next set of codes under the “else” indent.

“If statement” is not necessarily limited to two conditions only. You can chuck in as many conditions as you would like. Let’s add some conditions to this program.

We are defining another condition with a boolean variable. Let it be:

if_cold = True

Now we can add a third condition to our program. It works as this

is_hot = False

if_cold = True

if is_hot:

print("It's a hot day.")

print("Drink plenty of water")

elif is_cold:

print("It's a cold day.")

print("Wear warm clothes.")

else:

print("It's a lovely day")

print("Enjoy your day")

Now if it’s neither a hot day nor a cold one, then it’s a lovely day. Here we have used a new function “elif” to define a new condition between first “if” and last “else”. You can add as many “elif” as many you like.

Here’s an exercise for you. You know the rules.

Imagine the price of a house is $1M

“If the buyer has good credit.

They need to put down 10%

Otherwise,

They need to put 20%”

Write a program which decides the down payment based on the credit score.

Here is the solution for you guys: