barcode generator in c# windows application free Numeric Data Types in Visual C#.NET

Creation Denso QR Bar Code in Visual C#.NET Numeric Data Types

0 to 255 -922,337,203,685,477.5808 to 922,337,203,685,477.5807

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8 bytes A signed, fixed-point number with up to 15 digits to the left of the decimal and 4 digits to the right; used for financial or other calculations requiring a high degree of precision Can t be directly declared in VBA; requires the use of a Variant data type 12 bytes

+/- 79,228,162,514,264,337,593,543,950,335 with no decimal point and +/7.9228162514264337593543950335 with 28 digits behind the decimal point.

Table 4-7.

Negative values: -1.79769313486231E308 to -4.94065645841247E-324 Positive values: 4.94065645841247E-324 to 1.79769313486231E308 -32,768 to 32,767 -2,147,483,648 to 2,147,483,647 Negative values: -3.402823E38 to -1.401298E-45 Positive values: 1.401298E-45 to 3.402823E38

Some procedures will require a reference to a particular value that rarely, if ever, changes. Rather than repeatedly entering the same value, you can create a reference, called a constant, for it. Defining a constant lets you specify the actual value only once in your code and use the reference whenever you need it. VBA itself has many built-in constants, called intrinsic constants, designed to make it easier for you to work with the many functions available. For example, if you had a procedure to create a line chart, you could use the intrinsic constant xlDot to make the line dotted in appearance. Note You can display a list of the available intrinsic constants by typing intrinsic constants in the Help box in the Visual Basic Editor. You specify your own constants by using the Const statement, which works the same as the Dim statement with the exceptions that you must supply the value of the constant and only one constant can be declared on a line. The following lines declare two constants, the first a byte value with the number of days in December and the second a Single variable with an accepted value for pi.

As mentioned earlier, there are other data types besides numeric ones. Variables can also hold text values using the String data type. Strings can be either variable-length or fixed-length. 59

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Microsoft Office Excel 2003 Programming Inside Out Variable-length strings can hold approximately 2 billion (2 ^ 31) characters, subject to available memory, and fixed-length strings can hold about 65,000 characters (2 ^ 16). Both types of strings are declared similarly using the Dim statement just as was done with the numeric types. Fixed-length strings add extra code to specify the length of the string. The first line in the following code fragment specifies a variable-length string, and the second line specifies a fixed-length string of 25 characters:

Dim MyString as String Dim MyFixedString as String * 25

Strings that have been declared but have not yet had a value assigned to them are known as empty strings. To assign a value to a string variable, it needs to be enclosed within double quo tation marks. The following lines are examples of assigning values to strings:

MyString = "Hello world." MyFixedString = "This is a fixed string." MyEmptyString = ""

Note Fixed strings must be exactly 25 characters in length; therefore, the Visual Basic Editor will either add spaces or truncate the string so it is the proper length.

Dates and times are stored within the Date data type. The range of dates that can be stored is from January 1, 100, to December 31, 9999, with all times from 0:00:00 to 23:59:59. Although a Date variable can hold both a date and time, if you need only one element, only that element needs to be assigned to the variable; the other will be omitted from the variable. You can assign values to a date variable by enclosing a recognizable literal string within num ber signs (#). VBA can recognize dates and times in just about any format, but you should always be as explicit as possible to ensure the correct value is being used. Here are some examples of dates and times VBA can recognize.

MyDate = #15 July 1999# StartDate = #April 8, 2001# MyTime = #8:47 PM# StartingDateTime = #05/07/1992 15:56#