A function is reusable code that can be called anywhere in your program. Functions improve readability of your code: it’s easier for someone to understand code using functions instead of long lists of instructions.
On top of that, functions can be reused or modified which also improve testability and extensibility.
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We use this syntax to define as function:
def function(parameters): instructions return value
The def keyword tells Python we have a piece of reusable code (A function). A program can have many functions.
We can call the function using function(parameters).
#!/usr/bin/python def f(x): return(x*x) print(f(3))
The function has one parameter, x. The return value is the value the function returns. Not all functions have to return something.
We can pass multiple variables:
#!/usr/bin/python def f(x,y): print('You called f(x,y) with the value x = ' + str(x) + ' and y = ' + str(y)) print('x * y = ' + str(x*y)) f(3,2)
You called f(x,y) with the value x = 3 and y = 2 x * y = 6