Python Programming

We will first discuss calling a function, which intuitively means using the function.

We have already done this with a few built-in functions.

In the example below, we are calling the function len(), by passing the argument x to the function. The function then performs some computation and returns 3 (which is an object), and we then assign 3 to the variable length.

x = [1,5,8]
length = len(x)

A function call can also occur inside another function. The statement below calls the function id() with the argument x, and the resulting object (the memory location) is then passed on as the argument to the function print(). `

x = "composition"
print(id(x))

Note that print() is a function that does not return anything (more precisely, it returns None). Whatever it prints out is something it does within the function.

y = print("I return nothing!")
print(type(y))

More built-in functions

Let us call some built-in Mathematical functions: sum(), min(), max(), abs(), pow()

print(sum([2, 3]))
print(min([4, 1, 7]))
print(max([4, 1, 7]))
print(abs(-4))           # absolute value
print(pow(2, 4))         # 2 to the power of 4

Note that pow() takes two arguments, the base and the exponent. Thus, you can have functions that take multiple input.

A complete list of built-in Python functions is available here