1.7. C# variable

A variable is simply the name of a storage area for the program to operate on. In C#, each variable has a specific type, which determines the memory size and layout of the variable. Values within the range can be stored in memory and a series of operations can be performed on variables.

We have discussed various data types. The basic value types provided in C# can be broadly divided into the following categories:

Types	Give an example
Integer type	Sbyte, byte, short, ushort, int, uint, long, ulong and char
Floating point type	Float and double
Decimal type	Decimal
Boolean type	True or false value, specified valu
Null type	Data types that can be nullable

C# allows you to define variables of other value types, such as enum also allows you to define reference type variables, such as class . We will discuss these in later chapters. In this section, we only look at the basic variable types.

1.7.1. C# variable definition #

C# syntax for variable definition

<data_type> <variable_list>;

Here, data_type must be a valid C# data type, which can be char 、 int 、 float 、 double or other user-defined data types. variable_list can consist of one or more identifier names separated by commas.

Some valid variable definitions are as follows:

int i, j, k;
char c, ch;
float f, salary;
double d;

You can initialize when a variable is defined:

int i = 100;

1.7.2. C# variable initialization #

Variables are initialized (assigned) by an equal sign followed by a constant expression. The general form of initialization is:

variable_name = value;

Variables can be initialized when declared (specify an initial value). Initialization consists of an equal sign followed by a constant expression, as follows:

<data_type> <variable_name> = value;

Some examples:

int d = 3, f = 5;    /* Initialize d and f. */
byte z = 22;         /* Initialize z. */
double pi = 3.14159; /* Declare the approximate value of pi */
char x = 'x';        /* The value of variable x is 'x' */

Initializing variables correctly is a good programming habit, otherwise sometimes the program will produce unexpected results.

Take a look at the following example, using various types of variables:

Example #

namespace VariableDefinition
{
    class Program
    {
        static void Main(string[] args)
        {
            short a;
            int b ;
            double c;
            /* Actual initialization */
            a = 10;
            b = 20;
            c = a + b;
            Console.WriteLine("a = {0}, b = {1}, c = {2}", a, b, c);
            Console.ReadLine();
        }
    }
}

When the above code is compiled and executed, it produces the following results:

a = 10, b = 20, c = 30

1.7.3. Accept values from users #

System in the namespace Console class provides a function ReadLine() to receive input from the user and store it in a variable.