Task

You will now solve this task in a new way; specifically, you will store the calculation result in the same variable where you originally stored the entered number.

This is not necessarily a better solution, but you will learn how to build upon it further in later sections.

Solution

Here is the code:

static void Main(string[] args)
{
    // Input
    Console.Write("Enter a number: ");
    string input = Console.ReadLine();
    int number = Convert.ToInt32(input);

    // Calculation
    number = number + 10;

    // Result output
    Console.WriteLine("Number ten more greater is: " + number);

    // Waiting for Enter
    Console.ReadLine();
}

Discussion

The core statement of the solution is as follows: number = number + 10;. This statement is unusual in the sense that the same thing—the variable number—appears on both sides of the equal sign!

The computer executes the statement like this: “Take the present value of the variable number, add ten to it, and store the result as the new value of the variable number.” Thus, the net result of the statement is augmenting number’s value by ten.

Task

You will solve the previous exercise using the more concise compound assignment.

Solution

Here is the code:

static void Main(string[] args)
{
    // Input
    Console.Write("Enter a number: ");
    string input = Console.ReadLine();
    int number = Convert.ToInt32(input);

    // Calculation using compound assignment
    number += 10; // same as number = number + 10;

    // Result output
    Console.WriteLine("Number ten more greater is: " + number);

    // Waiting for Enter
    Console.ReadLine();
}

Task

I will show you a program that illustrates compound assignment in connection with subtraction, multiplication, and division (see Figure 13-2).

Figure 13-2 Compound assignment

Solution

Here is the code:

static void Main(string[] args)
{
    // Input
    Console.Write("Enter a number: ");
    string input = Console.ReadLine();
    int number = Convert.ToInt32(input);
    Console.WriteLine();

    // With subtraction
    number -= 5; // same as number = number - 5;
    Console.WriteLine("After decrease by 5: " + number);

    // With multiplication
    number *= 10; // same as number = number * 10;
    Console.WriteLine("Ten times greater: " + number);

    // With division
    number /= 2; // same as number = number / 2;
    Console.WriteLine("Decreased to one half: " + number);

    // Waiting for Enter
    Console.ReadLine();
}

Task

You’ll now get acquainted with the increment operator (++) and the decrement operator (--), as shown in Figure 13-3.

Figure 13-3 Increment and decrement operators

Solution

Here is the code:

static void Main(string[] args)
{
    // Input
    Console.Write("Enter a number: ");
    string input = Console.ReadLine();
    int number = Convert.ToInt32(input);

    // Increasing by 1 using INCREMENT OPERATOR
    number++; // same as number = number + 1;
    Console.WriteLine("Increased by 1: " + number);

    // Decreasing by 1 using DECREMENT OPERATOR
    number--; // same as number = number - 1;
    Console.WriteLine("Back again: " + number);

    // Waiting for Enter                                                                      
    Console.ReadLine();
}

Task

This task will get you familiar with text concatenations using compound assignment (see Figure 13-4).

Figure 13-4 Text concatenations using compound assignment

Solution

Here is the code:

static void Main(string[] args)
{
    // Initial value (empty text)
    string books = "";

    // Appending
    books += "Homage to Catalonia" + Environment.NewLine;
    books += "Silent Spring" + Environment.NewLine;
    books += "The beat of a different drum" + Environment.NewLine;

    // Output
    Console.WriteLine("Valuable books");
    Console.WriteLine("--------------");
    Console.WriteLine(books);

    // Waiting for Enter                                                                                                                                            
    Console.ReadLine();
}

Task

You will write a program that progressively sums three entered numbers. Sure, summing three numbers would be more conveniently done at once in a single line. However, I want to illustrate the important principle of progressive summation on a simple example and get you used to the idea before covering a more complex topic, namely, loops (see Figure 13-5).

Figure 13-5 Progressively summing three entered numbers

Solution

Here is the code:

static void Main(string[] args)
{
    // Preparation - variable to accumulate intemediate result
    int sum = 0;

    // Input - 1. number
    Console.Write("Enter first number: ");
    string input = Console.ReadLine();
    int number = Convert.ToInt32(input);

    // Adding first number to intermediate result
    sum += number;

    // Input - 2. number
    Console.Write("Enter second number: ");
    input = Console.ReadLine();
    number = Convert.ToInt32(input);

    // Adding second number to intermediate result
    sum += number;

    // Input - 3. number
    Console.Write("Enter third number: ");
    input = Console.ReadLine();
    number = Convert.ToInt32(input);

    // Adding third number to intermediate result
    sum += number;

    // Output
    Console.WriteLine();
    Console.WriteLine("Sum of entered numbers: " + sum);

    // Waiting for Enter
    Console.ReadLine();
}

Task

You will write a program that progressively accumulates names entered by the user. It will be interesting to make two accumulations; the first one is in the original order, and the second one is in the reverse order.

For simplicity, you will work with three values only (see Figure 13-6).

Figure 13-6 Progressively accumulating names

Solution

Here is the code:

static void Main(string[] args)
{
    // Preparation - variables to accumulate intermediate results
    string inOriginalOrder = "";
    string inReversedOrder = "";

    // Input of the first person
    Console.Write("Enter first person: ");
    string person = Console.ReadLine();

    // Appending the first person to intermediate result
    inOriginalOrder += person + Environment.NewLine;
    inReversedOrder = person + Environment.NewLine + inReversedOrder;

    // Input of the second person
    Console.Write("Enter second person: ");
    person = Console.ReadLine();

    // Appending the second person to intermediate result
    inOriginalOrder += person + Environment.NewLine;
    inReversedOrder = person + Environment.NewLine + inReversedOrder;

    // Input of the third person
    Console.Write("Enter third person: ");
    person = Console.ReadLine();

    // Appending the third person to intermediate result
    inOriginalOrder += person + Environment.NewLine;
    inReversedOrder = person + Environment.NewLine + inReversedOrder;

    // Output
    Console.WriteLine();
    Console.WriteLine("Entered persons");
    Console.WriteLine("---------------");
    Console.WriteLine(inOriginalOrder);

    Console.WriteLine("In reversed order");
    Console.WriteLine("-----------------");
    Console.WriteLine(inReversedOrder);

    // Waiting for Enter
    Console.ReadLine();
}