Passing Arguments to Functions

When you call a function, like print() , len(), or one you define yourself, you pass in values between the parenthesis, which are called arguments. Arguments can be any object, such as a list, integer, or string. For example, when we call len() on a list, the list is the argument. For example:

a = [1,2,3]
len(a)

In this case, when we make the function call len(a), the list a is the argument to the function len().

Some functions take multiple arguments. For example, the range() function. When we make a call like range(-10,10), we are using two arguments, the first of which specifies a starting integer, and the second of which specifies the stopping integer. Arguments are separated by a , (comma).

You may also recall that input() `` can may or may not take an **argument** which specifies prompt. For example, ``input() will just read input, but input('What is your name? ') will show What is your name? before reading input. Many functions have such optional arguments, which have a default value if not specified. We don’t have the knowledge yet to write our own, but be aware that they exist. In the case of input(), if the prompt isn’t specified, it will default to '', the empty string.

Some functions can even be called with no arguments. For example, calling print() with no arguments (nothing between the parenthesis) will result in a new line being printed and nothing else. We can create our own function that requires no arguments quite easily. For example, here is a function that requires no arguments and simply returns 1.

def return_one():
    return 1

Arguments can be a little perplexing, but they add a lot of power and flexibility to our function calls.