Parameters and arguments in C Sharp (C#) - Mini Project: Build & Apply

Understanding Parameters and Arguments in C#

📖 Scenario: Imagine you are creating a simple calculator program that can add two numbers. To do this, you will write a method that takes two numbers as input and returns their sum.

🎯 Goal: Build a C# program with a method that uses parameters to receive two numbers and returns their sum. Then call this method with arguments and display the result.

📋 What You'll Learn

Create a method with two parameters of type int

Call the method with two integer arguments

Store the returned sum in a variable

Print the sum to the console

💡 Why This Matters

🌍 Real World

Methods with parameters let programs receive input values to perform tasks like calculations, data processing, or controlling devices.

💼 Career

Understanding parameters and arguments is essential for writing reusable code and working with functions or methods in any software development job.

1

Create a method with parameters

Write a method called AddNumbers that takes two int parameters named num1 and num2. The method should return an int.

C Sharp (C#)

// Your code here

Hint

Define a method with static int AddNumbers(int num1, int num2) and return an integer value.

2

Add logic to return the sum

Inside the AddNumbers method, write code to return the sum of num1 and num2.

C Sharp (C#)

using System;

class Program
{
    static int AddNumbers(int num1, int num2)
    {
        // Your code here
    }

    static void Main()
    {
    }
}

Hint

Use the return keyword followed by num1 + num2 to return their sum.

3

Call the method with arguments

In the Main method, call AddNumbers with arguments 5 and 7. Store the result in an int variable called result.

C Sharp (C#)

using System;

class Program
{
    static int AddNumbers(int num1, int num2)
    {
        return num1 + num2;
    }

    static void Main()
    {
        // Your code here
    }
}

Hint

Call AddNumbers(5, 7) and assign it to int result.

4

Print the result

Add a Console.WriteLine statement in Main to print the value of result.

C Sharp (C#)

using System;

class Program
{
    static int AddNumbers(int num1, int num2)
    {
        return num1 + num2;
    }

    static void Main()
    {
        int result = AddNumbers(5, 7);
        // Your code here
    }
}

Hint

Use Console.WriteLine(result); to display the sum.

Practice

1. What is the role of a parameter in a C# method?

easy

A. It acts as a placeholder for values passed to the method.

B. It stores the result returned by the method.

C. It defines the method's name.

D. It calls another method inside the current method.

Solution

1. Step 1: Understand method definition

   Parameters are declared in the method signature to receive values.

2. Step 2: Differentiate parameters from other parts

   Parameters are not method names or return values but placeholders for inputs.

3. Final Answer:

   It acts as a placeholder for values passed to the method. -> Option A

4. Quick Check:

   Parameter = placeholder [OK]

Hint: Parameters hold input spots in methods [OK]

Common Mistakes:

• Confusing parameters with return values
• Thinking parameters are method names
• Mixing parameters with method calls

2. Which of the following is the correct way to define a method with one integer parameter named number in C#?

easy

A. void PrintNumber(number int) { }

B. void PrintNumber(int) { }

C. void PrintNumber(int number) { }

D. void PrintNumber(number) { }

Solution

1. Step 1: Recall C# parameter syntax

   Parameters require type first, then name: int number.

2. Step 2: Check each option

   void PrintNumber(int number) { } matches correct syntax; others have wrong order or missing names.

3. Final Answer:

   void PrintNumber(int number) { } -> Option C

4. Quick Check:

   Type before name in parameters [OK]

Hint: Parameter syntax: type then name [OK]

Common Mistakes:

• Swapping parameter type and name
• Omitting parameter name
• Using parentheses without parameter types

3. What will be the output of this C# code?

void Greet(string name) {
    Console.WriteLine($"Hello, {name}!");
}

Greet("Alice");

medium

A. Hello, Alice!

B. Hello, name!

C. Hello, !

D. Error: Missing argument

Solution

1. Step 1: Identify the parameter and argument

   The method Greet has a parameter name and is called with argument "Alice".

2. Step 2: Understand string interpolation output

   The output will replace {name} with "Alice" in the printed string.

3. Final Answer:

   Hello, Alice! -> Option A

4. Quick Check:

   Argument replaces parameter in output [OK]

Hint: Arguments fill parameters when calling methods [OK]

Common Mistakes:

• Printing parameter name literally
• Forgetting to pass argument
• Confusing parameter with variable

4. What is wrong with this method call?

void PrintSum(int a, int b) {
    Console.WriteLine(a + b);
}

PrintSum(5);

medium

A. Too many arguments passed.

B. Too few arguments passed.

C. Parameter types do not match arguments.

D. Method name is incorrect.

Solution

1. Step 1: Check method parameters

   The method PrintSum requires two integer parameters: a and b.

2. Step 2: Check method call arguments

   The call PrintSum(5); provides only one argument instead of two.

3. Final Answer:

   Too few arguments passed. -> Option B

4. Quick Check:

   Parameter count must match argument count [OK]

Hint: Count arguments to match parameters [OK]

Common Mistakes:

• Passing fewer arguments than parameters
• Ignoring method signature requirements
• Assuming default values without specifying

5. You want to create a method CalculateArea that takes two parameters width and height and returns their product. Which method signature and call correctly use parameters and arguments?

hard

A. Method: int CalculateArea(int width, int height)Call: CalculateArea(5);

B. Method: int CalculateArea(width, height)Call: CalculateArea(5, 10);

C. Method: void CalculateArea(int width, int height)Call: CalculateArea(5, 10);

D. Method: int CalculateArea(int width, int height)Call: CalculateArea(5, 10);

Solution

1. Step 1: Check method signature correctness

   Method: int CalculateArea(int width, int height)
   Call: CalculateArea(5, 10); correctly declares parameter types and names and returns int.

2. Step 2: Check method call arguments

   Method: int CalculateArea(int width, int height)
   Call: CalculateArea(5, 10); calls method with two integer arguments matching parameters.

3. Step 3: Analyze other options

   Method: int CalculateArea(width, height)
   Call: CalculateArea(5, 10); misses types in parameters; Method: int CalculateArea(int width, int height)
   Call: CalculateArea(5); passes only one argument; Method: void CalculateArea(int width, int height)
   Call: CalculateArea(5, 10); returns void, so no product returned.

4. Final Answer:

   Method with int parameters and int return, called with two arguments. -> Option D

5. Quick Check:

   Signature and call must match parameters and arguments [OK]

Hint: Match parameter types and argument count exactly [OK]

Common Mistakes:

• Omitting parameter types
• Passing wrong number of arguments
• Using void return when value needed