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Functions and return

A function is defined with def and can take parameters, often with default values. return ends the function and sends a value back to the caller. Without return, the function gives None.

\text{def } f(a, b{=}c): \ldots \text{return } e

f

returns the value of

e

;

b

gets default

c

if not supplied

Symbols

$a,\ b$	parameters
$c$	default value for $b$
$e$	the expression returned

Example

def f(a, b=2): return a * b

f(3) uses the default: $3\cdot 2 = 6$ .

A function with no return statement always gives None, not 0 or an empty string.

Practise functions and data structures for free →

← List comprehension · Dictionary (dict) →

Part of Programming with Python: Functions and data structures.