Appendix C
Standard Library Header Files
The interface to the C++ Standard Library consists of 78 header files, 26 of which present the C standard library. It’s often difficult to remember which header files you need to include in your source code, so this material provides a brief description of the contents of each header, organized into eight categories:
- The C Standard Library
- Containers
- Algorithms, iterators, and allocators
- General utilities
- Mathematical utilities
- Exceptions
- I/O Streams
- Threading library
THE C STANDARD LIBRARY
The C++ Standard Library includes the entire C Standard Library. The header files are generally the same, except for two points:
- The header names are <cname> instead of <name.h>.
- All the names declared in the header files are in the std namespace.
For backward compatibility, you can still include <name.h> if you want. However, that puts the names into the global namespace instead of the std namespace. We recommend avoiding this feature.
The following table provides a summary of the most useful functionality:
| HEADER FILE NAME | CONTENTS |
| <cassert> | assert() macro. |
 <ccomplex> |
Utilities to work with complex numbers. |
| <cctype> | Character predicates and manipulation functions, such as isspace() and tolower(). |
| <cerrno> | Defines errno expression. ... |
