Menu
What is the scope of a pragma directive? For example, if I say #pragma warning(disable: 4996) in a header file A that is included from a different file B, will that also disable all those warnings inside B? Or should I enable the warning at the end of file A again?
881
Pragma directives are machine-specific or operating system-specific by definition, and are typically different for every compiler. A pragma can be used in a conditional directive, to provide new preprocessor functionality. Or, use one to provide implementation-defined information to the compiler.
Does preprocessor really do something with #pragma? Yes, it evaluates it in translation phase 4: "Preprocessing directives are executed, macro invocations are expanded, and _Pragma unary operator expressions are executed."
The PRAGMA statement is an SQL extension specific to SQLite and used to modify the operation of the SQLite library or to query the SQLite library for internal (non-table) data.
The preprocessor directive #pragma is used to provide the additional information to the compiler in C/C++ language. This is used by the compiler to provide some special features.
It is till the end of the translation unit. Informally, a TU is the source file with its include files.
The usual pattern is this:
#pragma warning (push) //save #pragma warning (disable: xxxx) #pragma warning (disable: yyyy) ... //code #pragma warning (pop) //restore prev settings for example
//A.h #pragma once #pragma warning (disable: 1234) #include "b.h" //b.h #pragma once //when included after a.h 1234 will be disabled //c.cpp #include "a.h" //warnings 1234 from b.h is disabled //d.cpp #include "b.h" //warnings 1234 from b.h are not disabled #include "a.h" If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
