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Activity 4.2 Method Parameters

Introduction

Methods become much more powerful when we can send different pieces of information them to affect their behavior. The ability to pass information to a method is by using parameters. A parameter is simply a variable declared in a method signature. When we call a method with parameters, we can pass information that gets assigned to those parameter variables. The result is a method that can behave dynamically based on inputs passed to it.

In the example below, one parameter is declared, double number. A parameter is just a variable defined in a given context. It is scoped to its method, meaning number is only accessible inside of CubeNumber(). Once CubeNumber() is finished execution, the value of number is deleted.

The number 20 is passed to number. Data passed to a parameter is called an argument. Programmers regularly use the terms parameter and argument interchangably. Although they’re closely related, they are two distinct things.

Example

double CubeNumber(double number)
{
    return number * number * number;
}

// Pass the argument 20 to the parameter number
double answer = CubeNumber(20);
Console.WriteLine(answer);

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You can specify as many parameters as you need for a given method definition. Keep in mind, the order of arguments matters. In the example below, baseNumber is assigned 10, and exponent is assigned 3.

Multiple Parameters

double Power(double baseNumber, double exponent)
{
    double product = baseNumber;

    for (int i = 1; i < exponent; i++)
    {
        product = product * baseNumber;
    }

    return product;
}

Console.WriteLine(Power(10, 3));

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Example Video

Skills to Practice

Instructions

Setup

  1. Create a new C# console application. Name the project 4.2 Method Parameters.
  2. Click Create.

Code

// Check if an integer is even
// Parameters: number - number to be evaluated
// Returns: true if even, otherwise false
bool IsEven(int number)
{
    return number % 2 == 0;
}

// Check if an integer is odd
// Parameters: number - number to be evaluated
// Returns: true if odd, otherwise false
bool IsOdd(int number)
{
    return number % 2 == 1;
}

// Roll a die
// Parameters: numberOfSides - number of sides of the die
// Returns: number rolled as integer
int RollDie(int numberOfSides)
{
    Random random = new();
    return random.Next(1, numberOfSides + 1);
}

// Calculate wattage
// Parameters: voltage and amperage values
// Returns: watt value
double GetWattage(double volts, double amps)
{
    return volts * amps;
}

Console.WriteLine("1) IsEven()");
Console.WriteLine("2) IsOdd()");
Console.WriteLine("3) RollDie()");
Console.WriteLine("4) GetWattage()");

Console.Write("Choose method (1-4): ");
string input = Console.ReadLine();

if (input == "1")
{
    Console.Write("Enter integer: ");
    int n = Convert.ToInt32(Console.ReadLine());
    bool result = IsEven(n);
    Console.WriteLine($"Is {n} even? {result}");
}
else if (input == "2")
{
    Console.Write("Enter integer: ");
    int n = Convert.ToInt32(Console.ReadLine());
    bool result = IsOdd(n);
    Console.WriteLine($"Is {n} odd? {result}");
}
else if (input == "3")
{
    Console.Write("How many sides is the die? ");
    int sides = Convert.ToInt32(Console.ReadLine());
    int roll = RollDie(sides);
    Console.WriteLine($"You rolled a {roll}.");
}
else if (input == "4")
{
    Console.Write("Enter voltage: ");
    double v = Convert.ToInt32(Console.ReadLine());
    Console.Write("Enter amperage: ");
    double a = Convert.ToInt32(Console.ReadLine());
    double watts = GetWattage(v, a);
    Console.WriteLine($"{v}V x {a}A = {watts}W");
}
else
{
    Console.WriteLine("Invalid option selected.");
}

Debug

1) IsEven()
2) IsOdd()
3) RollDie()
4) GetWattage()
Choose method (1-4): 4
Enter voltage: 3.3
Enter amperage: 2
3.3V x 2A = 6.6W

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