Now that you know about booleans, you can use them along with the if keyword to make decisions:
bufday_today = True
if bufday_today:
print("happy bufday!")
else:
print("go away")happy bufday!
NOTE
The two print statements are indented. If the end of the current line ends in : and you press Enter, Thonny will automatically indent the
following lines. When you type else:, you’ll have to first manually unindent that line by pressing Backspace. You can manually indent lines by pressing Tab.
print("happy bufday!") was ran because the expression after if (bufday_today in this case) evaluated to True. If bufday_today had been False, then
print("go away") would’ve been run.
The simplest if statement goes like this:
if True:
print("hello world!")hello world!
As mentioned, the indented block of code only runs if the expression
that comes after if is true:
if False:
print("hello world!")You can have as many lines of code in the block as you like:
if True:
print("hello world!")
foo = 7 + 9
print(foo)hello world!
16
You can use else to run a different block of code if the statement is false:
age = 15
if age >= 16:
print("abc")
print("you're old enough to drive.")
else:
print(123)
print("go away")123
go away
NOTE
This section is the first time you’ve seen indented code.
Whenever you see a : at the end of a line, it means one or more
lines following will be indented. We do this a lot to organize code.
The empty space that comes before each indented line is important. Python uses it to know when a block of code ends. For example, notice the difference between this:
if 3 > 4:
print('abc')
print(123)
print('wow')and this:
if 3 > 4:
print('abc')
print(123)
print('wow')(If you don’t see it, try running the code).