What is an argument in a function?

Hi Joshua,

I'll see if I can explain it for you (it's been a while since I've dealt with Python).

Lets look at and break down the challenge.

def printer(count):
  print("Hi " * count)

The def key word is what is needed to "Define" a function in Python. This tells python that what follows is going to be a function.

"printer" is the name of the function being defined. This can be almost anything (within Python's namespace rules). Most languages don't allow names starting with numbers or symbols, nor can you use "Reserved" words for a given language. We could have called this function anything we wanted ("printNow", "toPrint", etc).

Now the argument. The argument goes between the parenthesis after the function name. This will be a value that is passed in when the function is called. Again, this can almost any name you want. Because of what the function does in this example, we could have called it ("printNumber", "x", "times", etc.). As long as the name of the argument chosen is used consistently throughout the function.

The print statement will print "Hi " the amount of times that was passed into "count" when the function was called. Remember, functions don't do anything until they are called. So, if we called the function and passed in 24 into the argument (named "count" here), the word "HI " (with a space) would print 24 times, and the function call would look like

printer(24)

So, basically, an argument is just another name for variable.

I hope this helps to clear some up. Keep Coding!

I like Jason's answer.

I would like to clarify a finer point on the semantics. The terms "variable", "parameter", and "argument" may be used to provide a more precises discussion in code.

A "variable" is used to hold the reference to object. When you assign:

string = "some characters"

The characters "some characters" are stored in memory and the variable string holds the reference to that spot in memory. "string" and the address it points to is stored in the namespace of the current object or module as a key/value pair. When you id() any variable, it is looked up in the namespace, and you get back the address of the object referred to by that variable. Variables can basically be thought of as object addresses.

When a function is defined, a list of expected parameters is defined between the parens. These parameters will receive references to objects when the function is called. That is, the parameters will become local variables with the addresses of the objects passed to the function.

When calling a function, a list of objects are provided for the function to operate on. These objects are called arguments.

So "arguments are passed to functions" and "a function can take an argument" makes more sense in this context. The phrase "define a function that takes a list" means it should expect a list to be passed as an argument, and the function should define a parameter to receive the list.

Once this soaks in, discussing code become much clearer.

More at [Wikipedia Parameters and Arguments](https://en.wikipedia.org/wiki/Parameter_(computer_programming\)#Parameters_and_arguments)

I'll let the Monty Python masters give a Lesson in Arguments (YouTube video)