Appendix B – Standard Library

This appendix is a summary of the library defined by the ANSI standard. The standard library is not part of the C language proper, but an environment that supports standard C will provide the function declarations and type and macro definitions of this library. We have omitted a few functions that are of limited utility or easily synthesized from others; we have omitted multi-byte characters; and we have omitted discussion of locale issues; that is, properties that depend on local language, nationality, or culture.  The functions, types and macros of the standard library are declared in standard headers:

   <assert.h>  <float.h>   <math.h>    <stdarg.h>  <stdlib.h>    <ctype.h>   <limits.h>  <setjmp.h>  <stddef.h>  <string.h>    <errno.h>   <locale.h>  <signal.h>  <stdio.h>   <time.h> A header can be accessed by   #include <header> Headers may be included in any order and any number of times. A header must be included outside of any external declaration or definition and before any use of anything it declares. A header need not be a source file. External identifiers that begin with an underscore are reserved for use by the library, as are all other identifiers that begin with an underscore and an upper-case letter or another underscore.