> ## Documentation Index > Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt > Use this file to discover all available pages before exploring further. # C# Typeof The `typeof` operator is a unary operator that obtains the `System.Type` instance representing a specific C# type at compile time. It takes a type name or a type parameter as its operand and returns the CLR metadata associated with that type, without requiring an allocated object instance. ```csharp theme={"dark"} Type typeInfo = typeof(int); ``` ## Technical Characteristics * **Compile-Time Resolution:** The C# compiler resolves the `typeof` expression to a metadata token. During execution, the Common Language Runtime (CLR) translates this token into a `System.Type` object reference. * **Operand Restrictions:** The operand must be a type name, a generic type parameter, or an unbound generic type. It cannot be a variable, an expression, or an object instance. To obtain type information from an instance at runtime, the `Object.GetType()` method is used instead. * **Reference Equality:** The CLR guarantees that exactly one `System.Type` object exists per type per application domain. Consequently, multiple invocations of `typeof` for the same type will return the exact same object reference in memory. ## Syntax Variations The operator handles various type categories, including primitives, custom objects, generics, and special system types. **Standard and Custom Types** ```csharp theme={"dark"} Type stringType = typeof(string); Type customType = typeof(MyClass); ``` **Void Type** The operator can evaluate the `void` keyword, returning the `System.Void` type. This is strictly used for reflection purposes, as `void` cannot be instantiated. ```csharp theme={"dark"} Type voidType = typeof(void); ``` **Arrays** The operator supports array types, including multi-dimensional and jagged arrays. ```csharp theme={"dark"} Type singleDimArray = typeof(int[]); Type multiDimArray = typeof(int[,]); ``` **Generic Types** `typeof` can evaluate both bound (constructed) and unbound generic types. For unbound generics, the syntax omits the type arguments but retains the commas to denote the arity (number of type parameters). ```csharp theme={"dark"} // Bound generic type Type boundList = typeof(List); // Unbound generic type (Arity 1) Type unboundList = typeof(List<>); // Unbound generic type (Arity 2) Type unboundDict = typeof(Dictionary<,>); ``` **Generic Type Parameters** When used within a generic class or method, `typeof` can evaluate the generic type parameter `T`. The actual `System.Type` returned will depend on the closed constructed type provided at runtime. ```csharp theme={"dark"} public class GenericClass { public Type GetParameterType() { return typeof(T); } } ```

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