The C runtime system is part of the Common Runtime Environment CRTE. When CRTE is used in BS2000 operating systems without POSIX, the C runtime system offers more than 300 predefined functions, including all the functions defined in the ANSI/ISO standard (as well as ISO-C Amendment 1 to ISO/IEC 9899:1990), and around 50 BS2000-specific extensions. These functions serve as a convenient aid in programming many tasks for which no higher-level language facilities are provided in C itself. Some examples of such programming tasks include:
processing of files (open, close, position, read, write, etc.)
processing of individual characters or strings (search, change, copy, delete etc.)
processing of multibyte and wide characters
processing of type
long long integerdynamic memory management (allocation and deallocation of storage areas, etc.)
access to operating system functions (system commands, utility routines, etc.)
mathematical functions (trigonometric, logarithmic etc.)
The functions are available either as source program sections (macros) or in the form of precompiled program segments (modules). In this manual the term “function” is used to include both types, unless it is necessary to make a distinction between the two.
The required function declarations, definitions of constants, data types and macros, as well as the function macros themselves are incorporated in “include files” (often referred to in
C literature as “standard include files”, “include headers” etc.). These include files are source program sections which can be addressed in the C program via #include directives and are temporarily copied to the program during each compilation.
All the functions and header files are stored in CRTE libraries as library elements.
A detailed description of how to access the CRTE libraries during the compilation, linkage and execution of a C or C++ program is provided in the C and C++ User Guides.