{"id":6042,"date":"2020-12-03T16:36:37","date_gmt":"2020-12-03T16:36:37","guid":{"rendered":"https:\/\/www.modernescpp.com\/index.php\/bit-manipulation-with-c-20\/"},"modified":"2023-06-26T09:36:28","modified_gmt":"2023-06-26T09:36:28","slug":"bit-manipulation-with-c-20","status":"publish","type":"post","link":"https:\/\/www.modernescpp.com\/index.php\/bit-manipulation-with-c-20\/","title":{"rendered":"Bit Manipulation with C++20"},"content":{"rendered":"

This post concludes my presentation of library features in C++20. Today I am writing about the class std::source_location<\/code> and a few functions for bit manipulation.<\/p>\n

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\"TimelineCpp20CoreLanguage2\"std::source_location<\/code><\/h2>\n

std::source_location<\/code> represents information about the source code. This information includes file names, line numbers, and function names. The information is precious when you need information about the call site for debugging, logging, or testing purposes. The class std::source_location<\/code> is the better alternative for the predefined C++11 macros __FILE__<\/code> and __LINE__<\/code> and should, therefore, be used.<\/p>\n

The following table shows the interface of std::source_location<\/code>.<\/p>\n

\"sourceLocation\"<\/p>\n

The call std::source_location::current()<\/code> creates a new source location object src. sr<\/code>c represents the information of the call site. Now, no C++ compiler supports std::source_location<\/code>. Consequently, the following program sourceLocation.cpp<\/code> is from cppreference.com\/source_location<\/a>.<\/p>\n

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\/\/ sourceLocation.cpp<\/span>\r\n\/\/ from cppreference.com<\/span>\r\n\r\n#include <iostream><\/span>\r\n#include <string_view><\/span>\r\n#include <source_location><\/span>\r\n \r\nvoid<\/span> log<\/span>(std::<\/span>string_view message,\r\n         const<\/span> std::<\/span>source_location&<\/span> location =<\/span> std::<\/span>source_location::<\/span>current())\r\n{\r\n    std::<\/span>cout <<<\/span> \"info:\"<\/span>\r\n              <<<\/span> location.file_name() <<<\/span> ':'<\/span>\r\n              <<<\/span> location.line() <<<\/span> ' '<\/span>\r\n              <<<\/span> message <<<\/span> '\\n'<\/span>;\r\n}\r\n \r\nint<\/span> main<\/span>()\r\n{\r\n    log(\"Hello world!\"<\/span>);  \/\/ info:main.cpp:19 Hello world!<\/span>\r\n}\r\n<\/pre>\n<\/div>\n
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The output of the program is part of its source code.<\/p>\n
C++20 makes it quite comfortable to access or manipulate bits or bit sequences.<\/p>\n<\/p>\n
Bit Manipulation<\/h2>\n
Thanks to the new type std::endian, you get the endianness of a scalar type.<\/p>\n
Endianness<\/h3>\n