Question

What is the difference between an argument and a return value? How many arguments can a function call have? How many return values?

Short answer

Arguments are inputs to a function; a return value is the output. Functions can have many arguments but typically only one return value, which can be a compound object with multiple values.

Step-by-step solution

Understanding Arguments

Arguments are inputs that you pass to a function when you call it. They provide the data that the function operates on. For example, in a function defined as `def add(a, b):`, `a` and `b` are parameters, and during a call `add(3, 5)`, 3 and 5 are the arguments.

Understanding Return Values

A return value is the output that a function gives back after completing its operation. In the `add` function example, the line `return a + b` would give you a return value of 8 if you called `add(3, 5)`.

Number of Arguments in a Function Call

A function call can have as many arguments as the function is defined to accept. There is no fixed limit imposed by the language itself, but practicality and readability suggest keeping the number of arguments manageable, typically fewer than 7-10.

Number of Return Values from a Function

Generally, a function can return a single object, but Python allows this object to be a tuple, list, or dictionary, which may contain multiple values. Thus, a function can effectively return multiple values packaged in a compound object.

Key concepts

return values

Return values are the outcomes that a Python function delivers once it has completed its task. When a function performs its calculations or data manipulations, it often needs to give back a result for further use. This result is known as a return value. For instance, a function designed to add two numbers might return the sum of those numbers. You create a return value using the `return` statement inside the function.

• A function without a return statement gives a special value called `None`, which indicates the absence of a return value.
• While typically a function returns one object, this object can be of any data type, including lists or tuples, which can hold multiple items.

Understanding return values is crucial, as they allow you to capture the result of a function call and use it elsewhere in your code, enhancing the flow and structure of your programs.

Python functions

Python functions are blocks of reusable code that perform a specific task. They help to organize code logically, making it easier to maintain and understand. Functions are defined using the `def` keyword, followed by the function name and a set of parentheses. Inside the parentheses, you may specify parameters, which are placeholders for the data your function needs to execute.

• Functions can be called multiple times, which saves time and prevents repetition.
• They're an essential part of creating modular code and support a method of programming known as `procedural programming`.

To define a function, structure your code like this: `def function_name(parameters):`. Inside the function, write the code that should run whenever the function is called. Remember, writing clear and concise functions will be immensely helpful as your coding projects grow more complex.

function calls

A function call is the method used to execute a function that you've defined. To "call" a function, you write the function's name followed by parentheses. If the function requires arguments, include these within the parentheses, separated by commas. For example, calling a function named `add` with arguments might look like `add(3, 5)`.

• A function call activates the code within the function, which uses any provided arguments to perform its task.
• The act of calling a function causes it to "run", returning any specified return values back to the place where the function was called.

Function calls are a fundamental concept because they allow the compartmentalized and organized code within functions to be used as needed throughout your Python program.

number of arguments

The number of arguments is determined by how a function is defined. Each parameter inside a function's definition expects a corresponding argument when the function is called. Although Python doesn't place a strict limit on the number of arguments you can pass to a function, it's generally recommended to keep this number reasonable.

• Having too many arguments can make functions difficult to read and understand.
• Most functions are designed with fewer than 7-10 arguments to maintain simplicity and clarity.

In cases where you need more flexibility, Python supports variable-length argument lists using the `*args` and `**kwargs` syntax, allowing you to send a variable number of arguments to a function, which is especially useful for dealing with undetermined argument requirements.