What is the purpose of ‘var’ in C#?

In C#, the ‘var’ keyword is used for implicit type inference. It allows the compiler to infer the type of a variable based on the right side of an assignment expression, and use that type for variable declaration and initialization.

Using the ‘var’ keyword can simplify code, reduce redundant type declarations, and enhance code readability and maintainability. It can be used when the variable’s type is already clear at assignment and there is no need to explicitly specify the type.

For example:

var name = "John"; // 推断变量name为string类型
var age = 25; // 推断变量age为int类型
var isStudent = true; // 推断变量isStudent为bool类型

// 可以在声明时不指定变量类型，而是使用var关键字进行类型推断
var sum = AddNumbers(10, 20); // 推断变量sum为AddNumbers方法返回的类型

It is important to note that variables declared with the var keyword determine their type at compile time and cannot be changed once determined. Therefore, the var keyword cannot be used to declare variables without initialized values, and the right side of the expression should have a clear type when using the var keyword.