Conditionals

If statement

Here are a few things to notice about the if statement:

• The if statement starts with if, it continues with price == 0.0 and it ends with :.

• Use the == operator to check if the price is equal to 0.0. Don't confuse == with = (= is a variable assignment operator in Python; we use it to assign values to variables — it doesn't tell us anything about equality).

• Indent ratings.append(rating) four spaces to the right relative to the if statement.

Multiple conditions

we can combine two or more conditions together into a single if statement using the and keyword. In the two diagrams below, we can use and to simultaneously check whether an app is both free and has a gaming genre.

app_1_price = 0
app_1_genre = 'Games'

if app_1_price == 0 and app_1_genre == 'Games':
    print('This is a free game!')

print(app_1_price == 0 and app_1_genre == 'Games')

Output
This is a free game!
True

app_2_price = 19
app_2_genre = 'Games'

if app_2_price == 0 and app_2_genre == 'Games':
    print('This is a free game!')

print(app_2_price == 0 and app_2_genre == 'Games')

Output
False

Notice above that code like app_1_price == 0 and app_1_genre == 'Games' outputs a single Boolean value.

Using or in conditions

if genre == 'Social Networking' or genre == 'Games':
        games_social_ratings.append(rating)

else statement

The code within the body of an else clause executes only if the if statement that precedes it resolves to False

if False:
    print(1)
else:
    print(2)

Output
2

else if (elif)

The code within the body of an elif clause executes only under the following circumstances:

• The preceding if statement (or the other preceding elif clauses) resolves to False; and

• The condition specified after the elif keyword evaluates to True.

Comparison Operators