Constant in C#.NET

Draw Code 128B in C#.NET Constant

the digit 1)

double float decimal bool bool char char (the character newline) char (the character whose numeric value is hex 123)1 string string (an empty string)

hex is short for hexadecimal (numbers in base 16 rather than base 10)

Humans don t treat different types of counting numbers differently For example, a normal person (as distinguished from a C# programmer) doesn t think about the number 1 as being signed, unsigned, short, or long Although C# considers these types to be different, even C# realizes that a relationship exists between them For example, the following code converts an int into a long:

int nValue = 10; long lValue; lValue = nValue;

An int variable can be converted into a long because any value of an int can be stored in a long and because they are both counting numbers C# makes the conversion for you automatically without comment

A conversion in the opposite direction can cause problems, however For example, the following is illegal:

Some values that you can store in a long do not fit in an int (4 billion, for example) C# generates an error in this case because data may be lost during the conversion process This type of bug is difficult to catch But what if you know that the conversion is okay For example, even though lValue is a long, maybe you know that its value can t exceed 100 in this particular program In that case, converting the long variable lValue into the int variable nValue would be okay You can tell C# that you know what you re doing by means of a cast:

long lValue = 10; int nValue; nValue = (int)lValue;

In a cast, you place the name of the type you want in parentheses and put it immediately in front of the value you want to convert This cast says, Go ahead and convert the long lValue into an int I know what I m doing In retrospect, the assertion that you know what you re doing may seem overly confident, but it s often valid A counting number can be converted into a floating point number automatically, but a cast from a floating point into a counting number requires a cast, as follows:

double dValue = 100; long lValue = (long)dValue;

All conversions to and from a decimal require a cast In fact, all numeric types can be converted into all other numeric types through the application of a cast Neither bool nor string can be converted directly into any other type Built-in C# functions can convert a number, character, or boolean into its string equivalent For example, you can convert the bool value true into the string true ; however, you cannot consider this a direct conversion The bool true and string true are completely different things

4

Performing a little arithmetic Doing some logical arithmetic Complicating matters with compound logical operators

athematicians create variables and manipulate them in various ways, adding them, multiplying them, and here s a toughie even integrating them 3 describes how to declare and define variables However, it says nothing about how to use variables to get anything done after you ve declared them This chapter looks at the operations you can perform on variables to actually get something done Operations require operators, such as +, , =, <, and & I cover arithmetic, logical, and other operators in this chapter Writing programs that get things done is good You ll never make it as a C# programmer if your programs don t actually do something unless, of course, you re a consultant