pragma

问题 Hey guys I am having a some problems with SQLcipher db for android The documentation is not too descriptive so I could not figure it out. I am trying to modify the default number of iterations on sqlcipher for android, I am editing the notecipher app provided as demo app with sqlcipher, and want to increase the kdf_iter to i.e. 5000 By overriding the getWritableDatabase() method in the database helper i enter the pragma value just after the file is open with the password. I can open and

问题 I want to enable optimization in g++ without command line parameter. I know GCC can do it by writing #pragma GCC optimize (2) in my code. But it seems won't work in G++. This page may help: http://gcc.gnu.org/onlinedocs/gcc/Function-Specific-Option-Pragmas.html My compiler version: $ g++ --version g++ (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1 <suppressed copyright message> $ gcc --version gcc (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1 <suppressed copyright message> I worte some code like this: #pragma

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: #pragma - help understanding I saw the pragma many times,but always confused, anyone knows what it does?Is it windows only? 回答1: In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation. Thus, #pragma once serves the same purpose as #include guards, but with several

问题 The title says it all. Have #pragma once been standardized for C++0x? I don't know any compiler that doesn't provide an implementation of it, with almost always the same semantics and name. 回答1: All #pragma directives cause the implementation to behave in an implementation defined way. This hasn't changed between C++03 and the latest C++0x draft (n3225.pdf). Include guards are the portable alternative. 回答2: Sun C++ compiler (Solaris) does not implement it. And no, it's not in C++0x drafts.

问题 I have a c++ structure: struct a { char b; int c; int d[100]; }; The size of the struct should be 405 bytes. I saw that the size of the struct is 408 bytes. The reason is the alignment to 8 bytes after the integer "c". The array "d" should start at the 6th byte of the struct and not at the 9th byte. I used #pragma pack(1) but it didn't solve the problem. I cannot change the order of fields in the struct. Do you have any idea how can I solve this problem? Thanks! 回答1: The fault packing for

问题 My background is C# but I have to maintain some legacy (MS) C++. In that codebase I stumpled across: #pragma comment(lib, "OtherLib700.lib") where 700 is some versioning. Besides the lib is a DLL with the same name. I first thought that the program would be dependant upon the DLL but after removing it from the system the program still works. There exists a newer version of the DLL, though, which is named OtherLib900... It seems as though the program 'included' the code of the lib so that it's

问题 My background is C# but I have to maintain some legacy (MS) C++. In that codebase I stumpled across: #pragma comment(lib, "OtherLib700.lib") where 700 is some versioning. Besides the lib is a DLL with the same name. I first thought that the program would be dependant upon the DLL but after removing it from the system the program still works. There exists a newer version of the DLL, though, which is named OtherLib900... It seems as though the program 'included' the code of the lib so that it's

问题 Once in a while it's difficult to write C++ code that wouldn't emit warnings at all. Having warnings enabled is however a good idea. So it is often necessary to disable warnings around some specific construct and have them enables in all other pieces of code. I've seen two ways of doing that so far. The first one is to use #pragma warning( push ) and #pragma warning( pop ) : #pragma warning( push ) #pragma warning( disable: ThatWarning ) //code with ThatWarning here #pragma warning( pop ) The

问题 To test some database pieces of a work project, I decided test it using triggers due to a nightly job. The nightly job Wipes everything from temporary tables repopulates those tables from an outside database merges the temp tables into primary tables a couple other jobs For the purposes of these tests I am not inclined to alter the source databases, but as the nightly job wipes the tables I cant just put values in which would work for my tests. Due to the load processes, once they are

问题 When I create a MEX file in MATLAB, I'm in the habit of also creating a .m file with the same name, a function signature identical to the MEX file, and otherwise containing nothing but help text in the form of comments, that are then displayed when one types help myfcn . When one does this, a small side-effect is that MATLAB Code Analyzer picks up on the fact that the input and output arguments specified in the function signature are unused, and flags them with an orange underline. Recently I