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C# Variables

Containers for storing data values are Variables. The different types of variables are as follows:

  •  int- it stores the integers (whole numbers) without decimals. Ex. 245, -678
  •  double- it stores the floating point numbers, with decimals. For ex. 18.25 or -18.25. Upto 15 digit decimal point will be executed.
  •  char- stores single characters, such as ‘b’ or ‘C’. However, it can also be surrounded by double quotes.
  •  string – it usually stores text, such as “ Hello World”. These values are surrounded by double quotes.
  •  bool- values are stored with two states either true(1) or false(0).


Declaring or Creating Variables

To create a variable, its type should be specified and value should be assigned.

Syntax: type variableName = value;

where type is C# type( such as int or string), and variableName is name of variable( such as b or name). Equal sign is used to assign values to the variable.

Example
string name = “FindAndSolve”;

Console.WriteLine(name);

output

FindAndSolve


Constants

 The const keyword is useful for always storing same value, so our code won’t get messed up. Example: PI(3.1415…).

const int myNum = 124;

myNum = 1347; // error

Note: A constant variable cannot be declared without assigning a value. Otherwise, an error will occur.

Display Variables

WriteLine() method is used to display values of variable to console window. To combine both text and variable, + character should be used.

Example
string name = "FindAndSolve";

Console.WriteLine("Hello " + name);
output

Hello FindAndSolve

You can also use the + character to add a variable to another variable:

Example
string firstName = "FindAndSolve";
string lastName = "Online Tutorial";
string fullName = firstName + lastName;
Console.WriteLine(fullName);
output

FindAndSolve Online Tutorial


For numeric values, the + character works as a mathematical operator (notice that we use int (integer) variables here):

Example
int x = 10;

int y = 7;
Console.WriteLine(x + y); // Print the value of x + y
output

17

From the example above, you can expect:

  • x stores the value 10
  •  y stores the value 7
  •  Then we use the WriteLine() method to display the value of x + y, which is 17.


Declaring Many Variables

To declare more than one variable of the same type, use a comma-separated list:

Example
int x = 7, y = 8, z = 15;

Console.WriteLine(x + y + z);
output

30


C# Identifiers

All C# variables must be identified with unique names called identifiers. It can be short names ( a and b) or more descriptive names( age, sum, totalVolume).

Note: To create the code which is understand and maintained, it is recommended to use descriptive names.

Example
// Good
int minutesPerHour = 60;
// OK, but not so easy to understand what m actually is int m = 60;
General rules for naming variables:
  • Names contain digits, letters, underscore character(_)
  • Must begin with a letter.
  • Should start with a lowercase letter and cannot contain whitespace.
  • These are case sensitive(“myVar” and “myvar” are different variables)
  • Reserved words ( like C# keywords, such as int or double) can’t be used as names.