Return values are an important part of programming. They make functions and procedures work better. In beginner programming classes, especially in computer science at the university level, understanding return values is key. They help send data back from functions. This ability allows programmers to write code that is easier to reuse and maintain.

First, return values let a function give back output after doing its job. This is especially important when a function is meant to calculate a result. For example, think about a function that adds two numbers. Without a return value, this function would do the math but wouldn’t be able to share the answer with the rest of the code. Here’s a simple example in Python:

def sum(a, b):
    return a + b

In this example, the sum function takes two numbers (or arguments) and returns their total. The "return" part is crucial because it sends the answer back to where the function was called. This way, functions can become more than just lines of code—they can play an important role in how a program works.

Return values also help manage data in a program. When a function gives back a value, that value can be stored in a variable, sent to another function, or used in loops and conditions. This makes managing data flow easier. For example:

result = sum(5, 10)
print(result)  # This will show: 15

Here, the answer from the sum function is stored in the variable result, which can be used later in the program. This shows that return values help organize the flow of data better.

Return values offer flexibility, too. Functions can return different values based on different situations. For example, a function that checks user input might return an error message if the input is wrong, or it might return the correct processed data if the input is good. Look at this example:

def process_input(user_input):
    if not isinstance(user_input, int):
        return "Error: Input must be an integer."
    return user_input * 2

In this case, the process_input function checks if the input is an integer. If it’s not, it sends back an error message. If it is, it returns the number multiplied by two. This shows how return values can help guide a program’s actions based on what the function gives back.

Return values aren’t just for basic tasks. They are also essential for handling errors and debugging. Many programmers use return values to show if something went right or wrong. This is especially helpful in languages that focus on catching errors. For example, a function might return a number that shows either success (like 0) or failure (any other number). This way, the calling code can decide what to do based on the function's result, like in this example:

int divide(int numerator, int denominator, double *result) {
    if (denominator == 0) {
        return -1; // Error: Division by zero
    }
    *result = (double)numerator / denominator;
    return 0; // Success
}

In this C example, the divide function returns an error code if there’s a division by zero. This shows that return values can share important data and help manage the state of the program. This leads to stronger and more reliable code.

Another great thing about return values is that they make code easier to read and maintain. When functions clearly return values, it’s easy for other programmers to understand what the function does just by looking at the return. This means better organized code.

For instance, compare these two functions:

def get_user_age():
    # Assume this function collects user input
    return age

def prompt_for_age():
    print("What is your age?")

In the first function, the return value shows clearly what data is being processed. The second function just asks for input without giving any value back. This difference highlights how functions with return values show behavior and results more clearly.

In the professional world, having functions that return values is very important. This approach fits well with functional programming ideas. These ideas promote “pure” functions that give the same answer for the same input without side effects. This leads to better predictions about how software behaves and makes it easier to test.

Return values also help with advanced programming concepts, like higher-order functions. Many modern programming styles encourage using functions that can return other functions. This shows how important return values are for creating complex behaviors in a simple way. For example:

def make_multiplier(factor):
    def multiplier(x):
        return x * factor
    return multiplier

In this case, make_multiplier gives back a new function, multiplier, that multiplies its input by the original factor. This ability to return functions allows for strong programming ideas like closures and currying, showing that return values are not just data but also a way to add important functionality.

Return values also help keep related tasks together. This makes code more organized. For example, using return values in lists or other data types lets results from multiple function calls work together. Here’s an example:

results = [sum(x) for x in data_sets]

In this case, a list is created using return values from the sum function applied to different sets of data. This highlights how return values help combine and manage data effectively.

Return values can also improve performance. When functions give direct outputs and avoid side effects, it can save resources and make the program run better. Functions that return values support a principle called immutability, which often leads to better memory and processing efficiency. This results in smoother-running applications.

In summary, return values are a key part of programming that make functions and procedures more effective. They help in sharing data, handling errors, simplifying program logic, and making code easier to read and maintain.

In computer science courses at the university level, it’s vital to teach the importance of return values. They are the foundation of functional programming and help students tackle real programming challenges. Learning about return values prepares students to think clearly and solve problems efficiently. Overall, return values are crucial for developing skilled programmers who can make meaningful contributions in computer science.