May 2004 - Posts

• How do I cast a string to an int, float, double, etc?

  You can use the Convert class or the Parse method of the built-in type you are casting to. i.e. string myStr = "123"; int myParsedInt = Int32.Parse(myStr); int myConvertedInt = Convert.ToInt32(myStr); This example uses the int type, but you can also use Read More... Posted Sunday, May 30, 2004 12:08 PM by CSharpFAQ | 20 Comments Filed under: C# Language and Compiler

• How are return values from a delegate handled?

  Q: How are multiple return values from a delegate handled? In C#, it's possible to write a delegate such as: delegate double GetResult(params double p); If there is more than one method on this delegate, there are multiple return values. A: In this situation, Read More... Posted Thursday, May 27, 2004 3:50 PM by CSharpFAQ | 4 Comments Filed under: C# Language and Compiler

• Why don't nullable relational operators return bool? instead of bool?

  Q: Why don't nullable relational operators return “bool?” instead of “bool“? Nullable types are a new feature of C# 2.0 . When dealing with nullable types, if you write the following: int? i = 15; int? j = 16; the type of i == Read More... Posted Tuesday, May 25, 2004 11:51 AM by CSharpFAQ | 8 Comments Filed under: C# Language 2.0

• Why can't I use the same variable as an inner loop does?

  Q: Why can't I do the following: namespace Bug { class Class1 { [ STAThread ] static void Main ( string [] args ) { for ( int i = 0; i < 100; i ++ ) { } int i = 0; } } } the compiler gives me an error on the “int i = 0;” part of the code. Read More... Posted Tuesday, May 18, 2004 2:59 PM by CSharpFAQ | 8 Comments Filed under: C# Language and Compiler

• How do I write a method that accepts a variable number of parameters?

  Q: How do I write a method that accepts a variable number of parameters? A: Languages like C and C++ have always offered some means for using and creating functions capable to accept a variable number of parameters. The most widely known example of a Read More... Posted Thursday, May 13, 2004 3:44 PM by CSharpFAQ | 5 Comments Filed under: C# Language and Compiler

• Why doesn't C# support static method variables?

  Q: In C++, it's possible to write a static method variable, and have a variable that can only be accessed from inside the method. C# doesn't provide this feature. Why? A: There are two reasons C# doesn't have this feature. First, it is possible to get Read More... Posted Tuesday, May 11, 2004 9:41 PM by CSharpFAQ | 6 Comments Filed under: C# Language and Compiler

• Why must attribute properties be read/write in C#?

  Q: Why must attribute properties be read/write in C#? In the C# language, when you define an attribute class, you can define both constructor arguments and properties. For example: class MyAttribute: Attribute { string name; int number; public MyAttribute(string Read More... Posted Tuesday, May 11, 2004 9:16 PM by CSharpFAQ | 5 Comments Filed under: C# Language and Compiler

• Why do I get the error "Object reference not set to an instance of an object"?

  The code is trying to access a member of a reference type variable that is set to null . Given the following class, let's examine some code that could be in the Main method: using System; class Foo { static void Main() { // foo has not been instantiated Read More... Posted Thursday, May 06, 2004 9:01 PM by CSharpFAQ | 11 Comments Filed under: C# Language and Compiler