我开始学习C ++并且读到增加警告级别是一个好主意，在编写代码时要更加小心。我使用的是Visual Studio 2015（社区版）
然而，在这样做之后，我收到了数百个错误（编辑：警告被视为错误，对不起），即使在基本程序中也是如此。这些都来自数学标题，他们说＆＃34;未引用的内联函数已被删除＆＃34;。似乎我不会使用的每种方法都会引发警告。
为什么会发生这种情况，我该如何解决？
答案 0 :(得分：13)
使用Visual C ++，您应该使用/W4，而不是/Wall，这是不切实际的。如果警告级别4仍然产生愚蠢的警告，例如从标准标题开始，然后考虑使用旧的MSVC "no sillywarnings" header或其合适的扩展名。最好是通过强制包含编译器选项。
为了在命令行中使用Visual C ++，我通常使用以下环境变量：
CL=/nologo /EHsc /GR /W4 /FI "iso646.h"
显然现在可以自动抑制来自系统标头的警告，所以这不是问题。
请注意，虽然神圣的C ++标准没有区分不同类型的诊断，但作为事实上的标准C ++编译器和链接器区分
<强>错误：
错误诊断意味着不会生成可执行文件（或目标文件）。
<强>警告：
警告诊断意味着某些事情可能是错误的，或者至少有些疑问，但假设您知道自己在做什么，编译器或链接器或其他工具继续进行。
您可以强制包含的相关MSVC特定标头（选项/FI），包括no sillywarnings标头的更新版本：
#pragma once
// p/cppx/core_language_support/compiler_specific/msvc_less_errors_as_warnings_please.hpp
// Copyright © Alf P. Steinbach 2015. Boost Software License 1.0.
#ifndef _MSC_VER
# error This file is specific to the MSVC (Microsoft Visual C++) compiler.
#endif
#pragma warning( error: 4566 ) // Character ... cannot be represented -- is error.
#pragma warning( error: 4627 ) // Source code has been ignored – is error.
#pragma once
// p/cppx/core_language_support/compiler_specific/msvc_more_warnings_please.hpp
// Copyright © Alf P. Steinbach 2015. Boost Software License 1.0.
#ifndef _MSC_VER
# error This file is specific to the MSVC (Microsoft Visual C++) compiler.
#endif
#pragma warning( push, 4 ) // Warning level 4 (max). MSVC /Wall is impractical.
#pragma once
// p/cppx/core_language_support/compiler_specific/msvc_no_sillywarnings_please.hpp
// Copyright © Alf P. Steinbach 2010 – 2015. Boost Software License 1.0.
#ifndef _MSC_VER
# error This file is specific to the MSVC (Microsoft Visual C++) compiler.
#endif
#ifndef CPPX_ALLOW_WP64
# // The /Wp64 option generates spurious warnings when a __w64 type argument selects
# // a correct overload with non-__w64 formal argument type, i.e. for <<. In newer
# // versions of MSVC this option is deprecated. It Really Annoyed a lot of people!
# ifdef _Wp64
# error Do not use the /Wp64 option: use a 64-bit compiler to detect 64-bit portability issues.
# endif
#endif
// The following are real warnings but are generated by almost all MS headers, including
// standard library headers, so it's impractical to leave them on.
#pragma warning( disable: 4619 ) // there is no warning number 'XXXX'
#pragma warning( disable: 4668 ) // XXX is not defined as a preprocessor macro
// The following are pure sillywarnings:
#pragma warning( disable: 4061 ) // enum value is not *explicitly* handled in switch
#pragma warning( disable: 4063 ) // case 'nn' is not a valid value for switch of enum 'Name'
#pragma warning( disable: 4099 ) // first seen using 'struct' now seen using 'class'
#pragma warning( disable: 4127 ) // conditional expression is constant
#pragma warning( disable: 4180 ) // qualifier applied to function type has no meaning
#pragma warning( disable: 4217 ) // member template isn't copy constructor
#pragma warning( disable: 4250 ) // inherits (implements) some member via dominance
#pragma warning( disable: 4251 ) // needs to have dll-interface to be used by clients
#pragma warning( disable: 4275 ) // exported class derived from non-exported class
#pragma warning( disable: 4347 ) // "behavior change", function called instead of template
#pragma warning( disable: 4355 ) // "'this': used in member initializer list
#pragma warning( disable: 4373 ) // override when arg types differ by const/volatile qualifiers
#pragma warning( disable: 4428 ) // MSVC 9: universal-character-name encountered in source
#pragma warning( disable: 4459 ) // local declaration hides global declaration
#pragma warning( disable: 4505 ) // unreferenced function has been removed
#pragma warning( disable: 4510 ) // default constructor could not be generated
#pragma warning( disable: 4511 ) // copy constructor could not be generated
#pragma warning( disable: 4512 ) // assignment operator could not be generated
#pragma warning( disable: 4513 ) // destructor could not be generated
#pragma warning( disable: 4610 ) // can never be instantiated user defined constructor required
#pragma warning( disable: 4623 ) // default constructor could not be generated
#pragma warning( disable: 4624 ) // destructor could not be generated
#pragma warning( disable: 4625 ) // copy constructor could not be generated
#pragma warning( disable: 4626 ) // assignment operator could not be generated
#pragma warning( disable: 4640 ) // a local static object is not thread-safe
#pragma warning( disable: 4646 ) // noreturn function should have a void return type
#pragma warning( disable: 4661 ) // a member of the template class is not defined.
#pragma warning( disable: 4670 ) // a base class of an exception class is inaccessible for catch
#pragma warning( disable: 4672 ) // a base class of an exception class is ambiguous for catch
#pragma warning( disable: 4673 ) // a base class of an exception class is inaccessible for catch
#pragma warning( disable: 4675 ) // resolved overload was found by argument-dependent lookup
#pragma warning( disable: 4702 ) // unreachable code, e.g. in <list> header.
#pragma warning( disable: 4710 ) // call was not inlined
#pragma warning( disable: 4711 ) // call was inlined
#pragma warning( disable: 4820 ) // some padding was added
#pragma warning( disable: 4917 ) // a GUID can only be associated with a class, interface or namespace
#pragma warning( disable: 4996 ) // MSVC 9: a C stdlib function has been "deprecated" (says MS)