Discuss the var keyword. When should it be used, and when should it be avoided?

The var keyword in C# is used to declare variables without explicitly specifying their type. Instead, the compiler infers the variable’s type based on the value assigned to it at compile time. For example:

var number = 42; // Inferred as int
var message = "Hello, world!"; // Inferred as string

When to Use var keyword

Readability: Use var when the type of the variable is obvious from the assigned value. For instance:

var person = new Person(); // Clearly a Person type
var total = 123.45; // Clearly a double

This helps keep your code clean and avoids redundancy.

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Complex Types: Use var when working with complex or anonymous types, where explicitly stating the type would be cumbersome:

var dictionary = new Dictionary<int, List<string>>();
var result = new { Name = "John", Age = 30 }; // Anonymous type

When to Avoid var keyword

Unclear Types: Avoid var when the type of the variable isn’t immediately clear, as it can reduce code readability:

var result = DoSomething(); // What type does DoSomething() return?

Explicitly stating the type here makes the code easier to understand.

Primitive Values: Avoid var for simple types like int, string, or bool unless it significantly improves readability:

int count = 10; // Prefer explicit type