Hello,大家好!

又见面了,我们一起来了解一下C++的万能头文件吧

我们在写c++程序时是否遇到过因为没有导入库文件而导致报错,或者多次导入库文件时导致重复导入?这时我们就可以使用万能头文件来解决需要写很多头文件的麻烦

首先,万能头文件是怎么写的可不能写错

#include

优点:

封装了c+标准库中几乎所有的头文件,引入之后就可以使用c++ 所有的头文件中的功能;

缺点:

1、并不是所有编译器都支持万能头文件的编译(比如说visual stido)

2、 限制了程序可移植性

3、由于在该头文件中包含了c++所有的头文件,在程序编写的过程中,程序中的变量

函数可能会和c++标准库中的命名冲突。

所以,在大型项目中尽量不要使用万能头文件!!!

万能头文件在DEV-C++中的定义是这样的(编程初学者都建议看一下):

// C++ includes used for precompiling -*- C++ -*-// Copyright (C) 2003-2020 Free Software Foundation, Inc.//// This file is part of the GNU ISO C++ Library.This library is free// software; you can redistribute it and/or modify it under the// terms of the GNU General Public License as published by the// Free Software Foundation; either version 3, or (at your option)// any later version.// This library is distributed in the hope that it will be useful,// but WITHOUT ANY WARRANTY; without even the implied warranty of// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the// GNU General Public License for more details.// Under Section 7 of GPL version 3, you are granted additional// permissions described in the GCC Runtime Library Exception, version// 3.1, as published by the Free Software Foundation.// You should have received a copy of the GNU General Public License and// a copy of the GCC Runtime Library Exception along with this program;// see the files COPYING3 and COPYING.RUNTIME respectively.If not, see// ./** @file stdc++.h *This is an implementation file for a precompiled header. */// 17.4.1.2 Headers// C#ifndef _GLIBCXX_NO_ASSERT#include #endif#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if __cplusplus >= 201103L#include #include #include #include #include #include #include #include #endif// C++#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if __cplusplus >= 201103L#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #endif#if __cplusplus >= 201402L#include #endif#if __cplusplus >= 201703L#include #include // #include #include #include #include #include #include #endif#if __cplusplus > 201703L#include #include #include #include #include #include #include // #include #include #endif

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