This Python Functions lesson is for a beginner. Read the short notes, run each example, then change one name or number and run it again.
A function packages steps under a name. def starts it. Call the function with parentheses.
Parameters receive values. return sends a value back. A function without return gives None.
Example 1: Start here
Keep a function on one job so the name stays honest.
def passed(score): # define the function; it runs when you call it
return score >= 70 # send this value back to the caller
print(passed(82))
print(passed(60))
Example 2: Define and call
The def line names the function. Nothing inside it runs until you call it.
def greet(name): # define the function; it runs when you call it
print("Hello", name) # a comma prints each value, with a space between
greet("Asha") # call the function
Example 3: Return a value
return sends a value back to the caller. print shows that value.
def double(n): # define the function; it runs when you call it
return n * 2 # send this value back to the caller
print(double(6))
Example 4: A default argument
If you omit the argument, the default is used.
def greet(name="learner"): # define the function; it runs when you call it
return "Hello " + name # send this value back to the caller
print(greet())
print(greet("Asha"))
Keep a function on one job so the name stays honest.
