Positional parameters

Learn to pass positional parameters.

Positional parameters

A positional parameter matches by its position in the call. Order matters:

def introduce(name, age):
    print(name, age)

introduce("Ayse", 28)   # Ayse 28
introduce(28, "Ayse")   # 28 Ayse

The second call runs but is meaningless; because 28 goes as name and "Ayse" as age. With positional calls you must respect the order.

Positional parameters are the most common form and handy for short calls.

Positional call limitations

In functions with many parameters, remembering the order gets hard. Then keyword calls are safer:

def create_user(name, age, role, active):
    ...

create_user("Ayse", 28, "admin", True)  # which value is what?

This call runs but is hard to read. To know which value goes to which parameter, you must check the function definition.

This problem is solved in the next lesson with keyword parameters.

Exercise Write a positional call

Define a function called introduce with name and age positional parameters. The body does print(name, age). Call it with introduce("Ayse", 28).

Show example solution

def introduce(name, age):
    print(name, age)
introduce("Ayse", 28)

Test yourself

In def f(a, b): ... called as f(1, 2), what is b?
- Raises an error
- 1
- 2
- None
Show answer

2 — Positionally the second value 2 goes to b.

Complete the second positional parameter

def introduce(name, ____):
    print(name, age)

Show answer

def introduce(name, age):
    print(name, age)

Match positional parameter concepts

order

Matching rule
f(1, 2)

Call shape
def f(a, b)

Definition shape
second value

Goes to b

Next lesson: Keyword parameters

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