发帖网站有哪些,重庆网站seo多少钱,专业设计网站排行榜,一个网站百度百科怎么做C17引入了std::filesystem库(文件系统库, filesystem library)。这里整理下std::filesystem::path的使用。 std::filesystem::path#xff0c;文件系统路径#xff0c;提供了对文件系统及其组件(例如路径、常规文件和目录)执行操作的工具。此path类主要用法包括#x… C17引入了std::filesystem库(文件系统库, filesystem library)。这里整理下std::filesystem::path的使用。 std::filesystem::path文件系统路径提供了对文件系统及其组件(例如路径、常规文件和目录)执行操作的工具。此path类主要用法包括注意windows和linux的结果差异windows上为\\而linux上为/ (1).构造函数、operator、assign:赋值; (2).append, operator/:追加; (3).concat, operator:连接; (4).clear:清除 (5).make_preferred将路径的通用格式视图(generic-format view of the path)中的所有目录分隔符(directory separator)转换为首选目录分隔符,例如在Windows上\是首选分隔符路径foo/bar将被转换为foo\bar (6).remove_filename删除path中的的文件名 (7).replace_filename将path中的原文件名用另一个文件名替换 (8).replace_extension将path中的原扩展名用另一个扩展名替换 (9).swap:交换两个path (10).string返回path的字符串格式 (11).compare按字典顺序比较两个path; (12).root_name, root_directory, root_path返回path的根名字、根目录、根路径 (13).relative_path, parent_path返回相对根路径的路径、返回父路径的路径 (14).filename, extension返回的文件名、扩展名 (15).empty检查path是否为空 (16).has_root_path, has_root_name, has_root_directory, has_relative_path, has_parent_path, has_filename, has_extension检查root_path、root_name、root_directory、relative_path、parent_path、filename、extension是否为空 (17).is_absolute, is_relative检查path是绝对路径还是相对路径 (18).hash_value: 计算path的哈希值 (19).operator, !, , , , , 按字典顺序比较两个path。 以下为测试代码注意windows和linux结果输出的差异
int test_filesystem_path()
{namespace fs std::filesystem;// 1. constructs a pathfs::path p1 /usr/lib;fs::path p2 C:/Program Files;fs::path p3(/usr/local);// 2. operatorp1 p1 / include; // move assignmentp2 p2 / NVIDIA GPU Computing Toolkit;// windows: p1:/usr/lib\\include, p2: C:/Program Files\\NVIDIA GPU Computing Toolkit// linux: p1:/usr/lib/include, p2: C:/Program Files/NVIDIA GPU Computing Toolkit std::cout p1: p1 , p2: p2 std::endl; // 3. assignstd::cout p3: p3 std::endl; // p3: /usr/localp3.assign(/usr/bin);std::cout p3: p3 std::endl; // p3: /usr/bin// 4. append, operator/fs::path p4 C:;p4.append(Git); // note: windows: C:Git not C://Git; linux: C:/Gitp3.append(include);p1 / include;p2 / NVIDIA;// windows: p4:C:Git, p3:/usr/bin\\include, p1:/usr/lib\\include\\include, p2:C:/Program Files\\NVIDIA GPU Computing Toolkit\\NVIDIA// linux: p4:C:/Git, p3:/usr/bin/include, p1:/usr/lib/include/include, p2:C:/Program Files/NVIDIA GPU Computing Toolkit/NVIDIAstd::cout p4: p4 , p3: p3 , p1: p1 , p2: p2 std::endl;// 5. concat, operatorp1 ;p1.concat(var);p1 lib;std::cout p1: p1 std::endl; // p1:varlib// 6. clearp1.clear();std::cout p1: p1 std::endl; // p1:// 7. make_preferredp1 a\\b\\c;p2 a/b/c;// windows: p1:a\\b\\c, p2:a\\b\\c// linux: p1:a\\b\\c, p2:a/b/cstd::cout p1: p1.make_preferred() , p2: p2.make_preferred() std::endl;// 8. remove_filenamep1 C:/Program Files/CUDA;p2 /usr/local/bin;p1 p1.remove_filename();p2 p2.remove_filename();// p1:C:/Program Files/, p2:/usr/local/, false, falsestd::cout p1: p1 , p2: p2 std::boolalpha , p1.has_filename() , p2.has_filename() std::endl;// 9. replace_filenamep1 C:/Program Files/CUDA;p2 /usr/local/bin;p1.replace_filename(include);p2.replace_filename(include);// p1:C:/Program Files/include, p2:/usr/local/includestd::cout p1: p1 , p2: p2 std::endl;// 10. replace_extensionp1 C:/Program Files/CUDA.jpg;p2 /usr/local/lena.jpg;p1.replace_extension(bmp);p2.replace_extension(.bmp);// p1:C:/Program Files/CUDA.bmp, p2:/usr/local/lena.bmpstd::cout p1: p1 , p2: p2 std::endl;// 11. swapp1 C:/Program Files/CUDA;p2 /usr/local/bin;p1.swap(p2);// p1:/usr/local/bin, p2:C:/Program Files/CUDAstd::cout p1: p1 , p2: p2 std::endl;// 12. stringauto str p1.string(); // note: cannot be: p1.string().c_str()std::cout str: str.c_str() std::endl; // str:/usr/local/bin// 13. generic_stringstr p1.generic_string();std::cout str: str std::endl; // str:/usr/local/bin// 14. comparep1 /usr/abc;p2 /usr/Abc;auto ret1 p1.compare(p2); // A: 65, a: 97auto ret2 p2.compare(p1);// windows: ret1:32, ret2:-32// linux: ret1:2097152, ret2:-2097152std::cout ret1: ret1 , ret2: ret2 std::endl;// 15. root_name, root_directory, root_path, relative_path, parent_path, filenamefs::path p fs::current_path();// windows: current path:E:\\GitCode\\Messy_Test\\prj\\x86_x64_vc12\\CppBaseTest, // root name:E:, root directory:\\, root path:E:\\, relative path:GitCode\\Messy_Test\\prj\\x86_x64_vc12\\CppBaseTest, // parent path:E:\\GitCode\\Messy_Test\\prj\\x86_x64_vc12, filename:CppBaseTest// linux: current path:/home/spring/GitCode/Messy_Test/prj/linux_cmake_CppBaseTest,// root name:, root directory:/, root path:/, relative path:home/spring/GitCode/Messy_Test/prj/linux_cmake_CppBaseTest,// parent path:/home/spring/GitCode/Messy_Test/prj, filename:linux_cmake_CppBaseTeststd::cout current path: p , root name: p.root_name() , root directory: p.root_directory() , root path: p.root_path() , relative path: p.relative_path() , parent path: p.parent_path() , filename: p.filename() std::endl;// 16. stem, extensionp1 E:\\x86_x64_vc12\\CppBaseTest.cpp;p2 /usr/local/linux.cpp;// windows: stem:CppBaseTest, extension:.cpp// linux: stem:E:\\x86_x64_vc12\\CppBaseTest, extension:.cppstd::cout stem: p1.stem() , extension: p1.extension() std::endl;// stem:linux, extension:.cppstd::cout stem: p2.stem() , extension: p2.extension() std::endl;// 17. empty, has_root_path, has_root_name, has_root_directory, has_relative_path, has_parent_path, has_filename, has_stem, has_extensionp fs::current_path();// windows: false,true,true,true,true,true,true,true,false// linux: false,true,false,true,true,true,true,true,falsestd::cout std::boolalpha p.empty() , p.has_root_path() , p.has_root_name() , p.has_root_directory() , p.has_relative_path() , p.has_parent_path() , p.has_filename() , p.has_stem() , p.has_extension() std::endl;// 18. is_absolute, is_relativep1 ../../images;p2 /usr/local;p3 E:\\x86_x64_vc12;p4 images/test;// windows: false,false,true,false,true,true,false,true// linux: false,true,false,false,true,false,true,truestd::cout std::boolalpha p1.is_absolute() , p2.is_absolute() , p3.is_absolute() , p4.is_absolute() , p1.is_relative() , p2.is_relative() , p3.is_relative() , p4.is_relative() std::endl;// 19. begin, endp fs::current_path();// windows: current path:E:\\GitCode\\Messy_Test\\prj\\x86_x64_vc12\\CppBaseTest// linux: current path:/home/spring/GitCode/Messy_Test/prj/linux_cmake_CppBaseTeststd::cout current path: p std::endl;// windows: E: | \\ | GitCode | Messy_Test | prj | x86_x64_vc12 | CppBaseTest |// linux: / | home | spring | GitCode | Messy_Test | prj | linux_cmake_CppBaseTest |for (auto it p.begin(); it ! p.end(); it)std::cout *it | ;std::cout std::endl;// non-member functions// 1. swapstd::cout p1: p1 , p2: p2 std::endl; // p1:../../images, p2:/usr/localfs::swap(p1, p2);std::cout p1: p1 , p2: p2 std::endl; // p1:/usr/local, p2:../../images// 2. hash_value/* windows:541593CE5A744D49 : .. / .. / imagesE20DE9FA0712ACAC : /usr/local448B5E8D233AB844 : E:\x86_x64_vc12 *//* linux:C5561B62D374C247 : ../../images8A5180B805D0D290 : /usr/localD937A950FC185671 : E:\x86_x64_vc12 */for (const auto s : {../../images, /usr/local, E:\\x86_x64_vc12})std::cout std::hex std::uppercase std::setw(16) fs::hash_value(s) : s \n;// 3. operator,!,,,,,p1 image/1.txt;p2 image/2.txt;// true,truestd::cout std::boolalpha (p1 ! p2) , (p1.parent_path() p2.parent_path()) std::endl;// 4. operator/p1 C:;p1 p1 / Users / admin;p2 /home;p2 p2 / local / bin;// windows: C:Users\\admin,/home\\local\\bin// linux: C:/Users/admin,/home/local/binstd::cout p1 , p2 std::endl;// 5. std::hash: std::hashstd::filesystem::path{}(p) is equal to std::filesystem::hash_value(p)/* windows:541593CE5A744D49 : .. / .. / imagesE20DE9FA0712ACAC: /usr/local448B5E8D233AB844 : E:\x86_x64_vc12 *//* linux:C5561B62D374C247 : ../../images8A5180B805D0D290 : /usr/localD937A950FC185671 : E:\x86_x64_vc12 */for (const auto s : { ../../images, /usr/local, E:\\x86_x64_vc12 })std::cout std::hex std::uppercase std::setw(16) std::hashfs::path{}(fs::path(s)) : s \n;return 0;
} 执行结果如下图所示注意windows和linux输出结果的差异 GitHubhttps://github.com/fengbingchun/Messy_Test
