Visual Fortran provides a complete National Language Support (NLS) library of language-localization routines and multibyte-character routines. You can use these routines to write applications in many different languages.
In many languages, the standard ASCII character set is not enough because it lacks common symbols and punctuation (such as the British pound sign), or because the language uses a non-ASCII script (such as Cyrillic for Russian) or because the language consists of too many characters for each to be represented by a single byte (such as Chinese).
In the case of many non-ASCII languages, such as Arabic and Russian, an extended single-byte character set is sufficient. You need only change the language locale and codepage, which can be done at a system level or within your program. However, Eastern languages such as Japanese and Chinese use thousands of separate characters that cannot be encoded as single-byte characters. Multibyte characters are needed to represent them.
Character sets are stored in tables called code sets. There are three components of a code set: the locale, which is a language and country (since, for instance, the language Spanish may vary among countries), the codepage, which is a table of characters to make up the computer's alphabet, and the font used to represent the characters on the screen. These three components can be set independently. Each computer running Windows operating systems comes with many code sets built into the system, such as English, Arabic, and Spanish. Multibyte code sets, such as Chinese and Japanese, are not standard but come with special versions of the operating system (for instance, Windows NT-J comes with the Japanese code set).
The default code set is obtained from the operating system when a program starts up. When you install your operating system, you should install the system supplied code sets. Thereafter, they are always available. You can switch among them by:
When you select a new locale, it becomes the default system locale, and will remain the default locale until you change it. Each locale has a default codepage associated with it, and a default currency, number, and date format.
You can change the currency, number, and date format in the International dialog box or the Regional Setting dialog box independently of the locale.
The locale determines the character set available to the user. The locale you select becomes the default for the NLS routines described in this section, but the NLS routines allow you to change locales and their parameters from within your programs. These routines are useful for creating original foreign-language programs or different versions of the same program for various international markets. Changes you make to the locale from within a program affect only the program. They do not change the system default settings.
The codepage you select, which can be set independently, controls the multibyte (MB routines) character routines described in this section. Only users with special multibyte-character code sets installed on their computers need to use MB routines. The standard code sets all use single-byte character code sets.
Note that in Visual Fortran source code, multibyte characters can be used only in character strings and source comments. They cannot be used within variable names or statements. Like program changes to the locale, program changes to codepages affect only the program, not the system defaults.
The NLS and MB routines are contained in the library DFNLS.LIB, which consists of DFNLS.MOD and DFNLS.F90. To access the routines, the following statement should be present in any program unit that uses NLS or MB routines:
USE DFNLS
This section includes a discussion of character sets and the NLS library routines: