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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> < html xmlns = "http://www.w3.org/1999/xhtml" > < head > < meta http-equiv = "Content-Type" content = "text/html; charset=UTF-8" / > < title > Headers< / title > < meta name = "generator" content = "DocBook XSL-NS Stylesheets V1.78.1" / > < meta name = "keywords" content = "ISO C++, library" / > < meta name = "keywords" content = "ISO C++, runtime, library" / > < link rel = "home" href = "../index.html" title = "The GNU C++ Library" / > < link rel = "up" href = "using.html" title = "Chapter / > < link rel = "prev" href = "using.html" title = "Chapter / > < link rel = "next" href = "using_macros.html" title = "Macros" / > < / head > < body > < div class = "navheader" > < table width = "100%" summary = "Navigation header" > < tr > < th colspan = "3" align = "center" > Headers< / th > < / tr > < tr > < td width = "20%" align = "left" > < a accesskey = "p" href = "using.html" > Prev< / a > < / td > < th width = "60%" align = "center" > Chapter < / th > < td width = "20%" align = "right" > < a accesskey = "n" href = "using_macros.html" > Next< / a > < / td > < / tr > < / table > < hr / > < / div > < div class = "section" > < div class = "titlepage" > < div > < div > < h2 class = "title" style = "clear: both" > < a id = "manual.intro.using.headers" > < / a > Headers< / h2 > < / div > < / div > < / div > < div class = "section" > < div class = "titlepage" > < div > < div > < h3 class = "title" > < a id = "manual.intro.using.headers.all" > < / a > Header Files< / h3 > < / div > < / div > < / div > < p >
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The C++ standard specifies the entire set of header files that
must be available to all hosted implementations. Actually, the
word "files" is a misnomer, since the contents of the
headers don't necessarily have to be in any kind of external
file. The only rule is that when one < code class = "code" > #include< / code > 's a
header, the contents of that header become available, no matter
how.
< / p > < p >
That said, in practice files are used.
< / p > < p >
There are two main types of include files: header files related
to a specific version of the ISO C++ standard (called Standard
Headers), and all others (TR1, C++ ABI, and Extensions).
< / p > < p >
Two dialects of standard headers are supported, corresponding to
the 1998 standard as updated for 2003, and the current 2011 standard.
< / p > < p >
C++98/03 include files. These are available in the default compilation mode, i.e. < code class = "code" > -std=c++98< / code > or < code class = "code" > -std=gnu++98< / code > .
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< / p > < div class = "table" > < a id = "table.cxx98_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ 1998 Library Headers" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > algorithm< / code > < / td > < td align = "left" > < code class = "filename" > bitset< / code > < / td > < td align = "left" > < code class = "filename" > complex< / code > < / td > < td align = "left" > < code class = "filename" > deque< / code > < / td > < td align = "left" > < code class = "filename" > exception< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > fstream< / code > < / td > < td align = "left" > < code class = "filename" > functional< / code > < / td > < td align = "left" > < code class = "filename" > iomanip< / code > < / td > < td align = "left" > < code class = "filename" > ios< / code > < / td > < td align = "left" > < code class = "filename" > iosfwd< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > iostream< / code > < / td > < td align = "left" > < code class = "filename" > istream< / code > < / td > < td align = "left" > < code class = "filename" > iterator< / code > < / td > < td align = "left" > < code class = "filename" > limits< / code > < / td > < td align = "left" > < code class = "filename" > list< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > locale< / code > < / td > < td align = "left" > < code class = "filename" > map< / code > < / td > < td align = "left" > < code class = "filename" > memory< / code > < / td > < td align = "left" > < code class = "filename" > new< / code > < / td > < td align = "left" > < code class = "filename" > numeric< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ostream< / code > < / td > < td align = "left" > < code class = "filename" > queue< / code > < / td > < td align = "left" > < code class = "filename" > set< / code > < / td > < td align = "left" > < code class = "filename" > sstream< / code > < / td > < td align = "left" > < code class = "filename" > stack< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > stdexcept< / code > < / td > < td align = "left" > < code class = "filename" > streambuf< / code > < / td > < td align = "left" > < code class = "filename" > string< / code > < / td > < td align = "left" > < code class = "filename" > utility< / code > < / td > < td align = "left" > < code class = "filename" > typeinfo< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > valarray< / code > < / td > < td align = "left" > < code class = "filename" > vector< / code > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p > < / p > < div class = "table" > < a id = "table.cxx98_cheaders" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ 1998 Library Headers for C Library Facilities" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > cassert< / code > < / td > < td align = "left" > < code class = "filename" > cerrno< / code > < / td > < td align = "left" > < code class = "filename" > cctype< / code > < / td > < td align = "left" > < code class = "filename" > cfloat< / code > < / td > < td align = "left" > < code class = "filename" > ciso646< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > climits< / code > < / td > < td align = "left" > < code class = "filename" > clocale< / code > < / td > < td align = "left" > < code class = "filename" > cmath< / code > < / td > < td align = "left" > < code class = "filename" > csetjmp< / code > < / td > < td align = "left" > < code class = "filename" > csignal< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > cstdarg< / code > < / td > < td align = "left" > < code class = "filename" > cstddef< / code > < / td > < td align = "left" > < code class = "filename" > cstdio< / code > < / td > < td align = "left" > < code class = "filename" > cstdlib< / code > < / td > < td align = "left" > < code class = "filename" > cstring< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ctime< / code > < / td > < td align = "left" > < code class = "filename" > cwchar< / code > < / td > < td align = "left" > < code class = "filename" > cwctype< / code > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < / tr > < /t
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C++11 include files. These are only available in C++11 compilation
mode, i.e. < code class = "literal" > -std=c++11< / code > or < code class = "literal" > -std=gnu++11< / code > .
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< / p > < p > < / p > < div class = "table" > < a id = "table.cxx11_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ 2011 Library Headers" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > algorithm< / code > < / td > < td align = "left" > < code class = "filename" > array< / code > < / td > < td align = "left" > < code class = "filename" > bitset< / code > < / td > < td align = "left" > < code class = "filename" > chrono< / code > < / td > < td align = "left" > < code class = "filename" > complex< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > condition_variable< / code > < / td > < td align = "left" > < code class = "filename" > deque< / code > < / td > < td align = "left" > < code class = "filename" > exception< / code > < / td > < td align = "left" > < code class = "filename" > forward_list< / code > < / td > < td align = "left" > < code class = "filename" > fstream< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > functional< / code > < / td > < td align = "left" > < code class = "filename" > future< / code > < / td > < td align = "left" > < code class = "filename" > initalizer_list< / code > < / td > < td align = "left" > < code class = "filename" > iomanip< / code > < / td > < td align = "left" > < code class = "filename" > ios< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > iosfwd< / code > < / td > < td align = "left" > < code class = "filename" > iostream< / code > < / td > < td align = "left" > < code class = "filename" > istream< / code > < / td > < td align = "left" > < code class = "filename" > iterator< / code > < / td > < td align = "left" > < code class = "filename" > limits< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > list< / code > < / td > < td align = "left" > < code class = "filename" > locale< / code > < / td > < td align = "left" > < code class = "filename" > map< / code > < / td > < td align = "left" > < code class = "filename" > memory< / code > < / td > < td align = "left" > < code class = "filename" > mutex< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > new< / code > < / td > < td align = "left" > < code class = "filename" > numeric< / code > < / td > < td align = "left" > < code class = "filename" > ostream< / code > < / td > < td align = "left" > < code class = "filename" > queue< / code > < / td > < td align = "left" > < code class = "filename" > random< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ratio< / code > < / td > < td align = "left" > < code class = "filename" > regex< / code > < / td > < td align = "left" > < code class = "filename" > set< / code > < / td > < td align = "left" > < code class = "filename" > sstream< / code > < / td > < td align = "left" > < code class = "filename" > stack< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > stdexcept< / code > < / td > < td align = "left" > < code class = "filename" > streambuf< / code > < / td > < td align = "left" > < code class = "filename" > string< / code > < / td > < td align = "left" > < code class = "filename" > system_error< / code > < / td > < td align = "left" > < code class = "filename" > thread< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > tuple< / code > < / td > < td align = "left" > < code class = "filename" > type_traits< / code > < / td > < td align = "left" > < code class = "filename" > typeinfo< / code > < / td > < td align = "left" > < code class = "filename" > unordered_map< / code > < / td > < td align = "left" > < code class = "filename" > unordered_set< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > utility< / code > < / td > < td align = "left" > < code class = "filename" > valarray< / code > < / td > < td align = "left" > < code class = "filename" > vector< / code > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p > < / p > < div class = "table" > < a id = "table.cxx11_cheaders" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ 2011 Library Headers for C Library Facilities" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > cassert< / code > < / td > < td align = "left" > < code class = "filename" > ccomplex< / code > < / td > < td align = "left" > < code class = "filename" > cctype< / code > < / td > < td ali
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In addition, TR1 includes as:
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< / p > < div class = "table" > < a id = "table.tr1_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ TR 1 Library Headers" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > tr1/array< / code > < / td > < td align = "left" > < code class = "filename" > tr1/complex< / code > < / td > < td align = "left" > < code class = "filename" > tr1/memory< / code > < / td > < td align = "left" > < code class = "filename" > tr1/functional< / code > < / td > < td align = "left" > < code class = "filename" > tr1/random< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > tr1/regex< / code > < / td > < td align = "left" > < code class = "filename" > tr1/tuple< / code > < / td > < td align = "left" > < code class = "filename" > tr1/type_traits< / code > < / td > < td align = "left" > < code class = "filename" > tr1/unordered_map< / code > < / td > < td align = "left" > < code class = "filename" > tr1/unordered_set< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > tr1/utility< / code > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p > < / p > < div class = "table" > < a id = "table.tr1_cheaders" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ TR 1 Library Headers for C Library Facilities" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > tr1/ccomplex< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cfenv< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cfloat< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cmath< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cinttypes< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > tr1/climits< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cstdarg< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cstdbool< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cstdint< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cstdio< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > tr1/cstdlib< / code > < / td > < td align = "left" > < code class = "filename" > tr1/ctgmath< / code > < / td > < td align = "left" > < code class = "filename" > tr1/ctime< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cwchar< / code > < / td > < td align = "left" > < code class = "filename" > tr1/cwctype< / code > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p > Decimal floating-point arithmetic is available if the C++
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compiler supports scalar decimal floating-point types defined via
< code class = "code" > __attribute__((mode(SD|DD|LD)))< / code > .
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< / p > < div class = "table" > < a id = "table.decfp_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ TR 24733 Decimal Floating-Point Header" border = "1" > < colgroup > < col align = "left" class = "c1" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > decimal/decimal< / code > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p >
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Also included are files for the C++ ABI interface:
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< / p > < div class = "table" > < a id = "table.abi_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "C++ ABI Headers" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > cxxabi.h< / code > < / td > < td align = "left" > < code class = "filename" > cxxabi_forced.h< / code > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p >
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And a large variety of extensions.
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< / p > < div class = "table" > < a id = "table.ext_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "Extension Headers" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > ext/algorithm< / code > < / td > < td align = "left" > < code class = "filename" > ext/atomicity.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/array_allocator.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/bitmap_allocator.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/cast.h< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ext/codecvt_specializations.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/concurrence.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/debug_allocator.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/enc_filebuf.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/extptr_allocator.h< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ext/functional< / code > < / td > < td align = "left" > < code class = "filename" > ext/iterator< / code > < / td > < td align = "left" > < code class = "filename" > ext/malloc_allocator.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/memory< / code > < / td > < td align = "left" > < code class = "filename" > ext/mt_allocator.h< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ext/new_allocator.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/numeric< / code > < / td > < td align = "left" > < code class = "filename" > ext/numeric_traits.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/pb_ds/assoc_container.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/pb_ds/priority_queue.h< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ext/pod_char_traits.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/pool_allocator.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/rb_tree< / code > < / td > < td align = "left" > < code class = "filename" > ext/rope< / code > < / td > < td align = "left" > < code class = "filename" > ext/slist< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ext/stdio_filebuf.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/stdio_sync_filebuf.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/throw_allocator.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/typelist.h< / code > < / td > < td align = "left" > < code class = "filename" > ext/type_traits.h< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > ext/vstring.h< / code > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < td class = "auto-generated" > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p > < / p > < div class = "table" > < a id = "table.debug_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "Extension Debug Headers" border = "1" > < colgroup > < col align = "left" class = "c1" / > < col align = "left" class = "c2" / > < col align = "left" class = "c3" / > < col align = "left" class = "c4" / > < col align = "left" class = "c5" / > < / colgroup > < tbody > < tr > < td align = "left" > < code class = "filename" > debug/bitset< / code > < / td > < td align = "left" > < code class = "filename" > debug/deque< / code > < / td > < td align = "left" > < code class = "filename" > debug/list< / code > < / td > < td align = "left" > < code class = "filename" > debug/map< / code > < / td > < td align = "left" > < code class = "filename" > debug/set< / code > < / td > < / tr > < tr > < td align = "left" > < code class = "filename" > debug/string< / code > < / td > < td align = "left" > < code class = "filename" > debug/unordered_map< / code > < / td > < td align = "left" > < code class = "filename" > debug/unordered_set< / code > < / td > < td align = "left" > < code class = "filename" > debug/vector< / code > < / td > < td class = "auto-generated" > < / td > < / tr > < / tbody > < / table > < / div > < / div > < br class = "table-break" / > < p > < / p > < div class = "table" > < a id = "table.profile_headers" > < / a > < p class = "title" > < strong > Table < / strong > < / p > < div class = "table-contents" > < table summary = "Extension Profile Headers" border = "1" > < colgr
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< / p > < p > First, mixing different dialects of the standard headers is not
possible. It's an all-or-nothing affair. Thus, code like
< / p > < pre class = "programlisting" >
#include < array>
#include < functional>
< / pre > < p > Implies C++11 mode. To use the entities in < array> , the C++11
compilation mode must be used, which implies the C++11 functionality
(and deprecations) in < functional> will be present.
< / p > < p > Second, the other headers can be included with either dialect of
the standard headers, although features and types specific to C++11
are still only enabled when in C++11 compilation mode. So, to use
rvalue references with < code class = "code" > __gnu_cxx::vstring< / code > , or to use the
debug-mode versions of < code class = "code" > std::unordered_map< / code > , one must use
the < code class = "code" > std=gnu++11< / code > compiler flag. (Or < code class = "code" > std=c++11< / code > , of course.)
< / p > < p > A special case of the second rule is the mixing of TR1 and C++11
facilities. It is possible (although not especially prudent) to
include both the TR1 version and the C++11 version of header in the
same translation unit:
< / p > < pre class = "programlisting" >
#include < tr1/type_traits>
#include < type_traits>
< / pre > < p > Several parts of C++11 diverge quite substantially from TR1 predecessors.
2014-09-21 17:33:12 +00:00
< / p > < / div > < div class = "section" > < div class = "titlepage" > < div > < div > < h3 class = "title" > < a id = "manual.intro.using.headers.cheaders" > < / a > The C Headers and < code class = "code" > namespace std< / code > < / h3 > < / div > < / div > < / div > < p >
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The standard specifies that if one includes the C-style header
(< math.h> in this case), the symbols will be available
in the global namespace and perhaps in
namespace < code class = "code" > std::< / code > (but this is no longer a firm
requirement.) On the other hand, including the C++-style
header (< cmath> ) guarantees that the entities will be
found in namespace std and perhaps in the global namespace.
< / p > < p >
Usage of C++-style headers is recommended, as then
C-linkage names can be disambiguated by explicit qualification, such
as by < code class = "code" > std::abort< / code > . In addition, the C++-style headers can
use function overloading to provide a simpler interface to certain
families of C-functions. For instance in < cmath> , the
function < code class = "code" > std::sin< / code > has overloads for all the builtin
floating-point types. This means that < code class = "code" > std::sin< / code > can be
used uniformly, instead of a combination
of < code class = "code" > std::sinf< / code > , < code class = "code" > std::sin< / code > ,
and < code class = "code" > std::sinl< / code > .
2014-09-21 17:33:12 +00:00
< / p > < / div > < div class = "section" > < div class = "titlepage" > < div > < div > < h3 class = "title" > < a id = "manual.intro.using.headers.pre" > < / a > Precompiled Headers< / h3 > < / div > < / div > < / div > < p > There are three base header files that are provided. They can be
2012-03-27 23:13:14 +00:00
used to precompile the standard headers and extensions into binary
files that may the be used to speed compiles that use these headers.
2014-09-21 17:33:12 +00:00
< / p > < div class = "itemizedlist" > < ul class = "itemizedlist" style = "list-style-type: disc; " > < li class = "listitem" > < p > stdc++.h< / p > < p > Includes all standard headers. Actual content varies depending on
2012-03-27 23:13:14 +00:00
language dialect.
< / p > < / li > < li class = "listitem" > < p > stdtr1c++.h< / p > < p > Includes all of < stdc++.h> , and adds all the TR1 headers.
< / p > < / li > < li class = "listitem" > < p > extc++.h< / p > < p > Includes all of < stdtr1c++.h> , and adds all the Extension headers.
< / p > < / li > < / ul > < / div > < p > How to construct a .gch file from one of these base header files.< / p > < p > First, find the include directory for the compiler. One way to do
this is:< / p > < pre class = "programlisting" >
g++ -v hello.cc
#include < ...> search starts here:
/mnt/share/bld/H-x86-gcc.20071201/include/c++/4.3.0
...
End of search list.
< / pre > < p > Then, create a precompiled header file with the same flags that
will be used to compile other projects.< / p > < pre class = "programlisting" >
g++ -Winvalid-pch -x c++-header -g -O2 -o ./stdc++.h.gch /mnt/share/bld/H-x86-gcc.20071201/include/c++/4.3.0/x86_64-unknown-linux-gnu/bits/stdc++.h
< / pre > < p > The resulting file will be quite large: the current size is around
thirty megabytes. < / p > < p > How to use the resulting file.< / p > < pre class = "programlisting" >
g++ -I. -include stdc++.h -H -g -O2 hello.cc
< / pre > < p > Verification that the PCH file is being used is easy:< / p > < pre class = "programlisting" >
g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 hello.cc -o test.exe
! ./stdc++.h.gch
. /mnt/share/bld/H-x86-gcc.20071201/include/c++/4.3.0/iostream
. /mnt/share/bld/H-x86-gcc.20071201include/c++/4.3.0/string
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< / pre > < p > The exclamation point to the left of the < code class = "code" > stdc++.h.gch< / code > listing means that the generated PCH file was used.< / p > < p > < / p > < p > Detailed information about creating precompiled header files can be found in the GCC < a class = "link" href = "http://gcc.gnu.org/onlinedocs/gcc/Precompiled-Headers.html" target = "_top" > documentation< / a > .
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