1. Open Microsoft Visual Studio.
2. The menu item File —> New —> Project (Файл -> Создать -> Проект).



3. In the window that opens, find Visual C# in the New Project Types section. From the Templates (Шаблоны) section, select Console Application (Консольное приложение).



4. Name the new solution (the field Solution Name) and call the project (the field Name (Имя)).



5. Save the project to a local disk in an easily accessible location (for example, D:\Projects).
6. Uncheck the Create directory for solution (Создать каталог для решения) checkbox to avoid multiplying directories unnecessarily.

1. For example, to add a new .cw file to the project with a name task2-L1.cs:





3. The result is:



4. Select the Program.cs file in the Solution Explorer window, copy code of the Main function and paste it to a new file. The result has to be so:


Paste the code into task2-L1:


5. The result is:



6. Place your cursor immediately after the open curly brace in the Main method, then press enter to create a new line. Place your code:



7. Exclude the file program.cs from the project to avoid the error (two Main functions cant exist in one project):



8. Don’t forget to place the text of the task as a comment before the program:

In C#, a statement is considered a command. Statements perform some action in your code such as calling a method or performing calculations. Statements are also used to declare variables and assign values to them.

Statements are formed from tokens. These tokens can be keywords, identifiers (variables), operators, and the statement terminator which is the semicolon (;). All statements in C# must be terminated with a semicolon.

Example:

int myVariable = 2;

In this example, the tokens are:

int is the data type used for the variable called myVariable.

The ‘=‘ is an assignment operator and is used to set the value of myVariable to 2.

The numeral 2 is known as a literal value. Literal simply means that it is, what it says it is. The numeral 2 cannot be anything but the numeral 2. You cannot assign a value to 2. You can assign the numeral 2 to a variable however, and that is what this C# statement is doing.

Finally, the statement ends with a semi-colon.

• Namespaces — the .NET Framework uses namespaces as a way to separate class files into related buckets or categories. It also helps avoid naming collisions in applications that may contain classes with the same name
• Classes — classes are the blueprints for reference types. They specify the structure an object will take when you create instances of the class
• Methods — they are discrete pieces of functionality in an application. They are analogous to functions in the non-object-oriented programming world
• Variables — these are identifiers or names, that you create to hold values or references to objects in your code. A variable is essentially a named memory location

When you create a variable in C# you must give it a data type. The data type tells the compiler and syntax checker what kind of information you intend to store in that variable. If you try to assign data that is not of that type, warnings or errors will inform you of this. This is part of the type-safe nature of C#.

You can assign a value to the variable at the time you create it or later in your program code. C# will not allow you to use an unassigned variable to help prevent unwanted data from being used in your application. The following code sample demonstrates declaring a variable and assigning a value to it.

int myVar = 0;

C# has some restrictions around identifiers that you need to be aware of.

First off, identifiers are case-sensitive because C# is a case-sensitive language. That means that identifiers such as myVar, _myVar, and myvar, are considered different identifiers.

Identifiers can only contain letters (upper case or lowercase), digits, and the underscore character. You can only start an identifier with a letter or an underscore character. You cannot start the identifier with a digit. myVar and _myVar are legal but 2Vars is not.

C# has a set of reserved keywords that the language uses. You should not use these keywords as an identifier in your code. You may choose to take advantage of the case-sensitivity of C# and use Double as an identifier to distinguish it from the reserved keyword double, but that is not a recommended approach.

When writing C# code, you will often use operators. An operator is a token that applies to operations on one or more operands in an expression. An expression can be part of a statement, or the entire statement. Examples include:

3 + 4 – an expression that will result in the literal value 4 being added to the literal value 3

counter++ – an expression that will result in the variable (counter) being incremented by one

Not all operators are appropriate for all data types in C#. As an example, in the preceding list the + operator was used to sum two numbers. You can use the same operator to combine two strings into one such as:

“Tom” + “Sawyer” which will result in a new string TomSawyer

You cannot use the increment operator (++) on strings however. In other words, the following example would cause an error in C#.

“Tom”++

The following table lists the C# operators by type.

• To input some data use a standart method ReadLine():

Console.ReadLine()

Console.ReadLine()

• To input data and set it to the integer variable n:

1.

int n = int.Parse(Console.ReadLine());

int n = int.Parse(Console.ReadLine());

where int means integer type of the variable n;
int.Parse — method to transform string type of the inputted data into integer type.
2.

int n = Convert.ToInt32(Console.ReadLine());

int n = Convert.ToInt32(Console.ReadLine());

• The same you can do if you use two variables: at first, the inputted data is saved into a string variable (s), afterward this value is transformed into integer and saved into integer type variable (n):

String s = Console.ReadLine(); int n = int.Parse(s);

String s = Console.ReadLine(); int n = int.Parse(s);