.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_stdatomic.h&action=edit)  
---|---  
  
####  [ [ edit ](/mwiki/index.php?title=cpp/header&action=edit&section=3 "Edit
section: Empty C headers") ]  Empty C headers

The headers [ ` <complex.h> ` ](/w/c/numeric/complex "c/numeric/complex") , [
` <ccomplex> ` ](/w/cpp/header/ccomplex "cpp/header/ccomplex") , [ `
<tgmath.h> ` ](/w/c/numeric/tgmath "c/numeric/tgmath") , and [ ` <ctgmath> `
](/w/cpp/header/ctgmath "cpp/header/ctgmath") do not contain any content from
the C standard library and instead merely include other headers from the C++
standard library.

[ <ccomplex> ](/w/cpp/header/ccomplex "cpp/header/ccomplex") (C++11)  (deprecated in C++17)  (removed in C++20)  |  Simply includes the header [ ` <complex> ` ](/w/cpp/header/complex "cpp/header/complex") [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_ccomplex&action=edit)  
---|---  
[ <complex.h> ](/w/cpp/header/ccomplex "cpp/header/ccomplex") (C++11)  |  Simply includes the header [ ` <complex> ` ](/w/cpp/header/complex "cpp/header/complex") [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_complex.h&action=edit)  
[ <ctgmath> ](/w/cpp/header/ctgmath "cpp/header/ctgmath") (C++11)  (deprecated in C++17)  (removed in C++20)  |  Simply includes the headers [ ` <complex> ` ](/w/cpp/header/complex "cpp/header/complex") and [ ` <cmath> ` ](/w/cpp/header/cmath "cpp/header/cmath") : the overloads equivalent to the contents of the C header ` tgmath.h ` are already provided by those headers  [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_ctgmath&action=edit)  
[ <tgmath.h> ](/w/cpp/header/ctgmath "cpp/header/ctgmath") (C++11)  |  Simply includes the headers [ ` <complex> ` ](/w/cpp/header/complex "cpp/header/complex") and [ ` <cmath> ` ](/w/cpp/header/cmath "cpp/header/cmath") [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_tgmath.h&action=edit)  
  
####  [ [ edit ](/mwiki/index.php?title=cpp/header&action=edit&section=4 "Edit
section: Meaningless C headers") ]  Meaningless C headers

The headers [ ` <ciso646> ` ](/w/cpp/header/ciso646 "cpp/header/ciso646") , [
` <cstdalign> ` ](/w/cpp/header/cstdalign "cpp/header/cstdalign") , and [ `
<cstdbool> ` ](/w/cpp/header/cstdbool "cpp/header/cstdbool") are meaningless
in C++ because the macros they provide in C are language keywords in C++.

[ <ciso646> ](/w/cpp/header/ciso646 "cpp/header/ciso646") (removed in C++20)  |  Empty header. [ The macros that appear in ` iso646.h ` in C ](/w/c/language/operator_alternative "c/language/operator alternative") are [ keywords in C++ ](/w/cpp/language/operator_alternative "cpp/language/operator alternative") [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_ciso646&action=edit)  
---|---  
[ <cstdalign> ](/w/cpp/header/cstdalign "cpp/header/cstdalign") (C++11)  (deprecated in C++17)  (removed in C++20)  |  Defines one [ compatibility macro constant ](/w/cpp/types "cpp/types") [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_cstdalign&action=edit)  
[ <cstdbool> ](/w/cpp/header/cstdbool "cpp/header/cstdbool") (C++11)  (deprecated in C++17)  (removed in C++20)  |  Defines one [ compatibility macro constant ](/w/cpp/types "cpp/types") [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_cstdbool&action=edit)  
[ <iso646.h> ](/w/cpp/header/ciso646 "cpp/header/ciso646") |  Has no effect  [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_iso646.h&action=edit)  
[ <stdalign.h> ](/w/cpp/header/cstdalign "cpp/header/cstdalign") (C++11)  |  Defines one [ compatibility macro constant ](/w/cpp/types "cpp/types") [ [edit] ](https://en.cppreference.com/mwiki/index.php?title=Template:cpp/header/dsc_stdalign.h&action=edit)  
[ <stdbool.h> ](/w/cpp/header/cstdbool "cpp/he