A function is a subroutine that returns a result (number, character string, etc.).
Imagine that you have ordered a product from an online store. From a programming point of view, you called some subroutine, and unlike a procedure, this subroutine must return a result - deliver the product you ordered. These subroutines are called
functions.
A function is formatted in exactly the same way as a procedure. The only difference from the procedure is the presence of a special operator
return, after which the value to be returned to the main program is written.
A function that returns the arithmetic mean of two integers would look like this:
def average(a, b):
avg = (a + b) / 2
return avg
It remains to understand how to call this function in the main program:
You should not call a function in the same way as a procedure:
average(10, 5)
The value returned by the function will be lost. It is as if the goods from the online store were not given to anyone, but thrown away. It is unlikely that the customer will like it.
It's more correct to
save the result in a variable (or
print it to the screen):
a = average(10, 5)
print(average(10, 5))
Need to remember!
- A function subroutine is formatted in the same way as a procedure.
- The function is called at the place in the program where you would put the value. For example, as a parameter of a print() statement or in an arithmetic expression.