Parameters and Arguments

A function becomes genuinely useful when it works on different input each time.

A parameter is the name in the definition, the placeholder. An argument is the actual value you pass when calling. The parameter is the empty seat; the argument is who sits in it.

Parameters

PYTHON

def greet(name):
    print("Welcome, " + name)

greet("Ama")
greet("Kofi")

JAVASCRIPT

function greet(name) {
  console.log("Welcome, " + name);
}

greet("Ama");
greet("Kofi");

Compare → Identical structure. `name` is the parameter; "Ama" and "Kofi" are arguments. Inside the function, name holds whatever was passed on that particular call.

EXAMPLE

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YOUR TURN

Your turn → Multiple parameters are matched by POSITION, first argument to first parameter. Swap the arguments and see the sentence break.

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Syntax has to be exact. Every quote, bracket and parenthesis needs its partner, and in Python the spaces at the start of a line count. One slip and the program won't run; the message will say where.

Default arguments let a parameter fall back to a value when no argument is given.

EXAMPLE

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YOUR TURN

Your turn → Identical syntax in both languages. Add a third parameter with its own default.

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Syntax has to be exact. Every quote, bracket and parenthesis needs its partner, and in Python the spaces at the start of a line count. One slip and the program won't run; the message will say where.

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