C# 5.0 Programmer's Reference

Appendix D Constant Declarations

Constant declarations are similar to the variable declarations described in Appendix C, “Variable Declarations.” The main differences are you must include an initialization statement to give the constant a value and you cannot change the value after the constant is initialized.

You may also need to use a literal type character to explicitly give a value’s type. For example, the following code attempts to create a float constant and set its value to 5.8. Unfortunately, C# interprets the literal string 5.8 as a double and not a float, so Visual Studio flags this as an error.

const float taxRate = 5.8;

To avoid this problem, or to make your code more explicit, you can follow a literal value with a literal type character to indicate the value’s data type, as in the following code.

const float taxRate = 5.8F;

The following table lists C#’s literal type characters.

Character	Data Type
U	uint
L	long
UL, LU	ulong
F	float
D	double
M	decimal

You can use either uppercase or lowercase for literal type characters.

You can also precede an integer literal with 0x or 0X to indicate that it is a hexadecimal value.