What are functions in programming languages?

In programming, a function is a block of code that performs a specific task and optionally returns a value. Functions are often used to organize and structure code, making it more readable and reusable.

Functions are defined with a specific syntax that varies depending on the programming language. For example, in Python, a function is defined using the def keyword, followed by the function name, a set of parentheses, and a colon. The code that makes up the function is indented underneath the definition line.

Here's an example of a simple Python function that takes two numbers as arguments, adds them together, and returns the result:

def add_numbers(a, b):
    result = a + b
    return result

print(add_numbers(3, 4))

This function is called add_numbers and takes two arguments a and b. The function performs the task of adding a and b together and assigns the result to a variable result. Finally, the function returns the value of result using the return statement.

When the function is called with the arguments 3 and 4 as in this example, the function will return 7

Another programming language like javascript, the function can be defined using function keyword.

function add_numbers(a, b){
    return a + b;
}
console.log(add_numbers(3, 4));

In this example the function add_numbers takes two arguments a and b and performs the task of adding a and b together and return the result. And when the function is called with the arguments 3 and 4 as in this example, the function will return 7

This is just a simple example, but in practice, functions can be much more complex and perform a wide variety of tasks. Functions can also take different types of arguments and return different types of values.

In programming, an argument is a value or a reference to a value that is passed to a function when it is called. Arguments are used to provide input to a function, which the function then uses to perform its task and optionally return a value.

When a function is defined, it is given a set of parameters, which are placeholders for the arguments that will be passed to the function when it is called. The number, order, and types of the parameters define the function's signature, which specifies how the function should be called.

For example, in the Python example I provided earlier, the function add_numbers is defined with two parameters a and b. These parameters act as placeholders for the actual arguments that will be passed to the function when it is called.

def add_numbers(a, b):
    result = a + b
    return result

When the function is called, the arguments are passed in the order in which the parameters are defined. For example:

print(add_numbers(3, 4))

In this example, the argument 3 is passed to the parameter a, and the argument 4 is passed to the parameter b.

You can also pass arguments by name, this is known as keyword arguments, and it allows you to specify which argument goes to which parameter, regardless of the order they appear. For example:

print(add_numbers(b=4, a=3))

In this example, the argument 3 is passed to the parameter a, and the argument 4 is passed to the parameter b regardless of the order of the arguments.

It's worth noting that a function can also have no parameters or no arguments, in this case, it can be called without passing any values.

In summary, arguments are the input values passed to a function when it is called, and the parameters are the placeholders for the arguments defined in the function signature. The arguments are used by the function to perform its task and optionally return a value.