C＃ 变量

C# 变量

变量 are containers for storing data values.

In C#, there are different types of variables (defined with different keywords), for example:

• int - stores integers (whole numbers), without decimals, such as 123 or -123
• double - stores floating point numbers, with decimals, such as 19.99 or -19.99
• char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes
• string - stores text, such as "Hello World!" String values are surrounded by double quotes
• bool - stores values with two states: true or false

Declaring (Creating) Variables

To create a variable, you must specify the type and assign it a value:

type variableName = value;

Where type is a C# type (such as int or string), and variableName is the name of the variable (such as x or name). The equal sign is used to assign values to the variable.

To create a variable that should store text, look at the following example:

string name = "John";
Console.WriteLine(name);

To create a variable that should store a number, look at the following example:

int myNum = 15;
Console.WriteLine(myNum);

You can also declare a variable without assigning the value, and assign the value later:

int myNum;
myNum = 15;
Console.WriteLine(myNum);

Note that if you assign a new value to an existing variable, it will overwrite the previous value:

int myNum = 15;
myNum = 20; // myNum is now 20
Console.WriteLine(myNum);

Other Types

A demonstration of how to declare variables of other types:

int myNum = 5;
double myDoubleNum = 5.99D;
char myLetter = 'D';
bool myBool = true;
string myText = "Hello";