
14 Expressions
14.5 Primary expressions
14.5.11 The typeof operator
Paragraph 11 The typeof operator is used to obtain the System.Type object for a type. typeof-expression : typeof ( type ) typeof ( void )
Paragraph 21 The first form of typeof-expression consists of a typeof keyword followed by a parenthesized type. 2 The result of an expression of this form is the System.Type object for the indicated type. 3 There is only one System.Type object for any given type. [Note: This means that for type T, typeof(T) == typeof(T) is always true. end note]
Paragraph 31 The second form of typeof-expression consists of a typeof keyword followed by a parenthesized void keyword. 2 The result of an expression of this form is the System.Type object that represents the absence of a type. 3 The type object returned by typeof(void) is distinct from the type object returned for any type. [Note: This special type object is useful in class libraries that allow reflection onto methods in the language, where those methods wish to have a way to represent the return type of any method, including void methods, with an instance of System.Type. end note] [Example: The example
using System;
class Test
{
static void Main() {
Type[] t = {
typeof(int),
typeof(System.Int32),
typeof(string),
typeof(double[]),
typeof(void) };
for (int i = 0; i < t.Length; i++) {
Console.WriteLine(t[i].FullName);
}
}
}
produces the following output: System.Int32 System.Int32 System.String System.Double[] System.VoidNote that int and System.Int32 are the same type. end example]
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