# Extra Clang Tools 6 documentation

## clang-tidy - modernize-deprecated-headers

# modernize-deprecated-headers

Some headers from C library were deprecated in C++ and are no longer welcome in C++ codebases. Some have no effect in C++. For more details refer to the C++ 14 Standard [depr.c.headers] section.

This check replaces C standard library headers with their C++ alternatives and removes redundant ones.

Improtant note: the Standard doesn’t guarantee that the C++ headers declare all the same functions in the global namespace. The check in its current form can break the code that uses library symbols from the global namespace.

- <assert.h>
- <complex.h>
- <ctype.h>
- <errno.h>
- <fenv.h> // deprecated since C++11
- <float.h>
- <inttypes.h>
- <limits.h>
- <locale.h>
- <math.h>
- <setjmp.h>
- <signal.h>
- <stdarg.h>
- <stddef.h>
- <stdint.h>
- <stdio.h>
- <stdlib.h>
- <string.h>
- <tgmath.h> // deprecated since C++11
- <time.h>
- <uchar.h> // deprecated since C++11
- <wchar.h>
- <wctype.h>

If the specified standard is older than C++11 the check will only replace headers deprecated before C++11, otherwise – every header that appeared in the previous list.

These headers don’t have effect in C++:

- <iso646.h>
- <stdalign.h>
- <stdbool.h>