C++标准库头文件<bits/stdc++.h>

在使用GNU GCC Compiler的时候，你可以包含一个头文件<bits/stdc++.h>，便可以使用C++中的各种标准库，而不用一个一个包含进来。

这在acm比赛中是一种常用的做法。接下来给大家看一下bits目录下的stdc++.h：

  1 // C++ includes used for precompiling -*- C++ -*-
  2 
  3 // Copyright (C) 2003-2014 Free Software Foundation, Inc.
  4 //
  5 // This file is part of the GNU ISO C++ Library.  This library is free
  6 // software; you can redistribute it and/or modify it under the
  7 // terms of the GNU General Public License as published by the
  8 // Free Software Foundation; either version 3, or (at your option)
  9 // any later version.
 10 
 11 // This library is distributed in the hope that it will be useful,
 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 // GNU General Public License for more details.
 15 
 16 // Under Section 7 of GPL version 3, you are granted additional
 17 // permissions described in the GCC Runtime Library Exception, version
 18 // 3.1, as published by the Free Software Foundation.
 19 
 20 // You should have received a copy of the GNU General Public License and
 21 // a copy of the GCC Runtime Library Exception along with this program;
 22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 23 // <http://www.gnu.org/licenses/>.
 24 
 25 /** @file stdc++.h
 26  *  This is an implementation file for a precompiled header.
 27  */
 28 
 29 // 17.4.1.2 Headers
 30 
 31 // C
 32 #ifndef _GLIBCXX_NO_ASSERT
 33 #include <cassert>
 34 #endif
 35 #include <cctype>
 36 #include <cerrno>
 37 #include <cfloat>
 38 #include <ciso646>
 39 #include <climits>
 40 #include <clocale>
 41 #include <cmath>
 42 #include <csetjmp>
 43 #include <csignal>
 44 #include <cstdarg>
 45 #include <cstddef>
 46 #include <cstdio>
 47 #include <cstdlib>
 48 #include <cstring>
 49 #include <ctime>
 50 
 51 #if __cplusplus >= 201103L
 52 #include <ccomplex>
 53 #include <cfenv>
 54 #include <cinttypes>
 55 #include <cstdalign>
 56 #include <cstdbool>
 57 #include <cstdint>
 58 #include <ctgmath>
 59 #include <cwchar>
 60 #include <cwctype>
 61 #endif
 62 
 63 // C++
 64 #include <algorithm>
 65 #include <bitset>
 66 #include <complex>
 67 #include <deque>
 68 #include <exception>
 69 #include <fstream>
 70 #include <functional>
 71 #include <iomanip>
 72 #include <ios>
 73 #include <iosfwd>
 74 #include <iostream>
 75 #include <istream>
 76 #include <iterator>
 77 #include <limits>
 78 #include <list>
 79 #include <locale>
 80 #include <map>
 81 #include <memory>
 82 #include <new>
 83 #include <numeric>
 84 #include <ostream>
 85 #include <queue>
 86 #include <set>
 87 #include <sstream>
 88 #include <stack>
 89 #include <stdexcept>
 90 #include <streambuf>
 91 #include <string>
 92 #include <typeinfo>
 93 #include <utility>
 94 #include <valarray>
 95 #include <vector>
 96 
 97 #if __cplusplus >= 201103L
 98 #include <array>
 99 #include <atomic>
100 #include <chrono>
101 #include <condition_variable>
102 #include <forward_list>
103 #include <future>
104 #include <initializer_list>
105 #include <mutex>
106 #include <random>
107 #include <ratio>
108 #include <regex>
109 #include <scoped_allocator>
110 #include <system_error>
111 #include <thread>
112 #include <tuple>
113 #include <typeindex>
114 #include <type_traits>
115 #include <unordered_map>
116 #include <unordered_set>
117 #endif

这样在编程的时候就可以这样子做：

 1 #include <bits/stdc++.h>
 2 
 3 using namespace std;
 4 
 5 int main()
 6 {
 7     while(true)
 8     {
 9         int n;
10         cin >> n;
11         if(n==-1) break;
12         cout << n*n << endl;
13     }
14     return 0;
15 }

如图：

简单方便不是吗？