#pragma once #pragma once是受到绝大多数现代编译器支持的非标准语用。当某个头文件中包含它时,指示编译器只对其分析一次,即使它在同一源文件中(直接或间接)被包含了多次也是如此。 阻止同一头文件的多次包含的标准方式是使用包含防护: #ifndef LIBRARY_FILENAME_H#define LIBRARY_FILENAME_H// 头文件的内容#end...
许多编译器也会实现有类似效果的非标准语用#pragma once:在已经包含相同文件(文件的身份以操作系统指定的方式确定)的时候禁止处理该文件。 如果h字符序列或q字符序列中包含了类似转义序列的序列,那么根据实现可能会导致错误,被处理为转义序列对应的字符,或者具有完全不同的含义。
Unlike header guards, this pragma makes it impossible to erroneously use the same macro name in more than one file. On the other hand, since with#pragma oncefiles are excluded based on their filesystem-level identity, this can't protect against including a header twice if it exists in more...
Many compilers also implement the non-standardpragma#pragma oncewith similar effects: it disables processing of a file if the same file (where file identity is determined in OS-specific way) has already been included. A sequence of characters that resembles an escape sequence inq-char-sequenceor...
std::once_flag flag; void foo() { } std::call_once(flag, foo); std::condition_variable 创建条件变量 std::condition_variable cond; 等待条件变量被通知 std::unique_lock<std::mutex> lock; extern bool predicate(); // 调用方式 1 cond.wait(lock); // 调用方式 2 cond.wait(lock, predic...
An iteration of a loop must not execute the sameomp ordereddirective more than once. An iteration of a loop must not execute more than one distinctomp ordereddirective. #pragma omp parallel for Description Theomp parallel fordirective effectively combines theomp parallelandomp fordirectives. This ...
'-=---suboption-+-' Command-line options in the-qoption_keywordformat are similar to on and off switches. Formost-qoptions, if a given option is specified more than once, the last appearance of that option on the command line is the one recognized by the compiler. For example,-qsourc...
Enables more aggressive optimizations on floating-point data. consistent The compiler uses default heuristics to determine results for different optimization levels or between different processors of the same architecture. strict Enables precise and except, disables contractions, and enables pragmastdc fenv_...
#pragma GCC diagnostic ignored "-Wformat-security" #endif#define MAT_HEADER_LENGTH 200void DisplayControlsPoints(FbxMesh* pMesh); void DisplayPolygons(FbxMesh* pMesh); void DisplayMaterialMapping(FbxMesh* pMesh); void DisplayTextureMapping(FbxMesh* pMesh); ...
std::once_flag flag; void foo() { } std::call_once(flag, foo); std::condition_variable 创建条件变量 std::condition_variable cond; 等待条件变量被通知 std::unique_lock<std::mutex> lock; extern bool predicate(); // 调用方式 1 cond.wait(lock); // 调用方式 2 cond.wait(lock, predic...