3.1 The C Locale

All the culture and language dependencies discussed in the previous section need to be represented in an operating system. This information is usually represented in a kind of language table, called a locale.

The X/Open consortium has standardized a variety of services for Native Language Support (NLS) in the programming language C. This standard is commonly known as XPG4. Internationalization services as well as localization support are included in X/Open's Native Language Support. The description below is based on this standard.

According to XPG4, the C locale is composed of several categories, which are given in Table 2.

Table 2 -- Categories of the C locale

The external representation of a C locale is usually as a file in UNIX. Other operating systems may use other representations. The external representation is transformed into an internal memory representation by calling the function setlocale(), as shown in Figure 4 below:

Figure 4 -- Transformation of a C locale from external to internal representation

Inside a program, the C locale is represented by one or more global data structures. The C library provides a set of functions that use information from those global data structures to adapt their behavior to local conventions. Examples of these functions and the information they cover are listed in Table 3:

Table 3 -- C locale functions and the information they cover

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