zzy979/ppp-code

《C++程序设计原理与实践》书中代码和习题解答

ppp-code's Issues

12.7节代码在Linux上编译失败

Job链接：https://github.com/ZZy979/PPP-code/actions/runs/4076716325/jobs/7024818373

错误信息：

/home/runner/work/PPP-code/PPP-code/ch12/shape_primitives.cpp: In function ‘int main()’:
/home/runner/work/PPP-code/PPP-code/ch12/shape_primitives.cpp:44:16: error: reference to ‘Font’ is ambiguous
   44 |     t.set_font(Font::times_bold);
      |                ^~~~
In file included from /home/runner/work/PPP-code/PPP-code/ch12/shape_primitives.cpp:1:
/home/runner/work/PPP-code/PPP-code/GUI/Graph.h:83:7: note: candidates are: ‘class Graph_lib::Font’
   83 | class Font {
      |       ^~~~
In file included from /usr/include/X11/Xlib.h:44,
                 from /home/runner/work/PPP-code/PPP-code/cmake-build/_deps/fltk-src/FL/x.H:37,
                 from /home/runner/work/PPP-code/PPP-code/cmake-build/_deps/fltk-src/FL/fl_draw.H:27,
                 from /home/runner/work/PPP-code/PPP-code/GUI/Graph.h:10,
                 from /home/runner/work/PPP-code/PPP-code/ch12/shape_primitives.cpp:1:
/usr/include/X11/X.h:100:13: note:                 ‘typedef XID Font’
  100 | typedef XID Font;
      |             ^~~~
gmake[2]: *** [ch12/CMakeFiles/shape_primitives.dir/build.make:76: ch12/CMakeFiles/shape_primitives.dir/shape_primitives.cpp.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:5052: ch12/CMakeFiles/shape_primitives.dir/all] Error 2
gmake: *** [Makefile:146: all] Error 2

解决方法：使用完全限定名称 Graph_lib::Font

MSVC编译器报错“文本后缀无效”

MSVC编译ch21/word_query.cpp报错：

MSBuild version 17.4.1+9a89d02ff for .NET Framework
  fltk.vcxproj -> D:\CLionProjects\PPP-code\cmake-build-debug-visual-studio-2022\_deps\fltk-build\lib\Debug\fltkd.lib
  word_query.cpp
D:\CLionProjects\PPP-code\ch21\word_query.cpp(1,1): warning C4819: 该文件包含不能在当前代码页(936)中表示的字符。请将该文件保存为 Unicode 格式以防止数据丢失 [D:\CLionProjects\PPP-code\cmake-build-debug-visual-studio-2022\ch21\word_query.vcxproj]
D:\CLionProjects\PPP-code\ch21\word_query.cpp(103,88): error C3688: 文本后缀“��|�”无效；未找到文文本运算符或文本运算符模板“operator """"��|�” [D:\CLionProjects\PPP-code\cmake-build-debug-visual-studio-2022\ch21\word_query.vcxproj]
D:\CLionProjects\PPP-code\ch21\word_query.cpp(105,37): error C2065: “RE_SINGLE_QUOTES”: 未声明的标识符 [D:\CLionProjects\PPP-code\cmake-build-debug-visual-studio-2022\ch21\word_query.vcxproj]

相关代码如下：

static const std::regex RE_DOUBLE_QUOTES("“|”"), RE_SINGLE_QUOTES("‘|’");

但是gcc编译器正常，GitHub Actions的build-visual-studio也正常。

怀疑是字符编码的问题：源代码是UTF-8编码，而MSVC默认使用GBK编码，如果源代码中包含中文字符（全角引号）就会编译失败。将源文件编码改为GBK后错误就消除了。

使用MinGW编译FLTK报错：narrowing conversion

提交 5dc031c 触发的Actions流水线报错：

https://github.com/ZZy979/PPP-code/actions/runs/6291461674/job/17079850502

In file included from C:/ProgramData/chocolatey/lib/mingw/tools/install/mingw64/x86_64-w64-mingw32/include/windows.h:70,
                 from D:\a\PPP-code\PPP-code\cmake-build\_deps\fltk-src\fluid\ExternalCodeEditor_WIN32.h:27,
                 from D:\a\PPP-code\PPP-code\cmake-build\_deps\fltk-src\fluid\ExternalCodeEditor_WIN32.cxx:14:
D:\a\PPP-code\PPP-code\cmake-build\_deps\fltk-src\fluid\ExternalCodeEditor_WIN32.cxx: In member function 'int ExternalCodeEditor::reap_editor(DWORD*)':
D:\a\PPP-code\PPP-code\cmake-build\_deps\fltk-src\fluid\ExternalCodeEditor_WIN32.cxx:491:10: error: narrowing conversion of '4294967295' from 'DWORD' {aka 'long unsigned int'} to 'int' [-Wnarrowing]
  491 |     case WAIT_FAILED: {    // failed
      |          ^~~~~~~~~~~
mingw32-make[2]: *** [_deps\fltk-build\fluid\CMakeFiles\fluid.dir\build.make:361: _deps/fltk-build/fluid/CMakeFiles/fluid.dir/ExternalCodeEditor_WIN32.cxx.obj] Error 1
mingw32-make[1]: *** [CMakeFiles\Makefile2:1451: _deps/fltk-build/fluid/CMakeFiles/fluid.dir/all] Error 2

从错误信息判断原因是FLTK源代码fluid\ExternalCodeEditor_WIN32.cxx中的缩小转换导致的。但是此前一直正常，本次提交运行的其他job也没报错，只有MinGW构建失败。

FLTK仓库已有相关issue：fltk/fltk#92、fltk/fltk#178、fltk/fltk#445，该bug已在1.4版本中修复，但目前尚未发布。

部分单测在macOS上运行失败

操作系统版本：macOS 12.5.1

$ c++ --version
Apple clang version 13.1.6 (clang-1316.0.21.2.5)
Target: x86_64-apple-darwin21.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

$ ctest
...
98% tests passed, 13 tests failed out of 661

Total Test time (real) =   9.01 sec

The following tests FAILED:
        155 - convert_length_unit_test_cm_compare (Failed)
        158 - convert_length_unit_test_inch_compare (Failed)
        161 - convert_length_unit_test_feet_compare (Failed)
        164 - convert_length_unit_v2_test_cm_compare (Failed)
        167 - convert_length_unit_v2_test_inch_compare (Failed)
        170 - convert_length_unit_v2_test_feet_compare (Failed)
        179 - convert_currency_test_pound_compare (Failed)
        191 - convert_currency_v2_test_pound_compare (Failed)
        200 - convert_currency_v2_test_baht_compare (Failed)
        230 - length_statistics_test_compare (Failed)
        411 - CalculatorV2LexerTest.Get (Failed)
        548 - temp_stats_test_run (Failed)
        549 - temp_stats_test_compare (Not Run)
Errors while running CTest

这些单测失败的原因：当数字后面紧跟一个非数字字符时，>>运算符在不同编译器的行为可能不同。例如，对于cin >> length >> unit，输入"2.5c"，不同编译器可能得到不同的结果。经过测试发现结果与数字后面的具体字符有关：

#include <iostream>
#include <sstream>
#include <string>

using namespace std;

int main() {
    for (int i = 'a'; i <= 'z'; ++i) {
        istringstream iss(string("2.5") + char(i));
        double d = -1;
        char c = ' ';
        iss >> d >> c;
        cout << bool(iss) << ' ' << d << ' ' << c << endl;
    }
    return 0;
}

测试机器上的clang编译器得到的结果为：

0 0  
0 0  
0 0  
0 0  
0 0  
0 0  
1 2.5 g
1 2.5 h
0 0  
1 2.5 j
1 2.5 k
1 2.5 l
1 2.5 m
0 0  
1 2.5 o
0 0  
1 2.5 q
1 2.5 r
1 2.5 s
1 2.5 t
1 2.5 u
1 2.5 v
1 2.5 w
0 0  
1 2.5 y
1 2.5 z

gcc编译器得到的结果为：

1 2.5 a
1 2.5 b
1 2.5 c
1 2.5 d
0 0  
1 2.5 f
1 2.5 g
1 2.5 h
1 2.5 i
1 2.5 j
1 2.5 k
1 2.5 l
1 2.5 m
1 2.5 n
1 2.5 o
1 2.5 p
1 2.5 q
1 2.5 r
1 2.5 s
1 2.5 t
1 2.5 u
1 2.5 v
1 2.5 w
1 2.5 x
1 2.5 y
1 2.5 z

因此，为了确保一致的行为，需要在数字和字符之间加一个空格。

数学函数错误码在不同编译器上结果不一致

提交 190f6c0 触发的Actions流水线运行单测在部分环境下失败：

https://github.com/ZZy979/PPP-code/actions/runs/6746001569

单测失败的程序为drill24-4.cpp，程序通过错误码errno或者浮点数异常fetestexcept()来判断标准数学函数sqrt()是否计算成功。输入为drill24-4_input.txt，预期输出为drill24-4_output.txt，实际结果：

操作系统	编译器	结果
Ubuntu	GNU GCC 11.4.0	成功
macOS	AppleClang 14.0.0	失败
Windows	MSVC 19.37.32825.0	失败
Windows	MinGW GCC 12.2.0	成功

在Windows上使用MinGW Makefiles编译、运行失败

问题1：在构建目标fltk_images时报错：

[ 31%] Building CXX object _deps/fltk-build/src/CMakeFiles/fltk_images.dir/Fl_PNG_Image.cxx.obj
D:/a/PPP-code/PPP-code/cmake-build/_deps/fltk-src/src/Fl_PNG_Image.cxx:44:14: fatal error: libpng/png.h: No such file or directory
   44 | #    include <libpng/png.h>
      |              ^~~~~~~~~~~~~~
compilation terminated.
gmake.exe[2]: *** [_deps/fltk-build/src/CMakeFiles/fltk_images.dir/build.make:167: _deps/fltk-build/src/CMakeFiles/fltk_images.dir/Fl_PNG_Image.cxx.obj] Error 1
gmake.exe[1]: *** [CMakeFiles/Makefile2:1054: _deps/fltk-build/src/CMakeFiles/fltk_images.dir/all] Error 2
gmake.exe: *** [Makefile:146: all] Error 2

解决方法：增加CMake选项-D OPTION_USE_SYSTEM_LIBJPEG=OFF -D OPTION_USE_SYSTEM_LIBPNG=OFF -D OPTION_USE_SYSTEM_ZLIB=OFF

问题2：构建成功，但可执行程序和单元测试运行失败：

        Start 322: AreaTest.Good
322/661 Test #322: AreaTest.Good ...........................................Exit code 0xc0000139
***Exception:   0.01 sec
        Start 323: AreaTest.Bad
323/661 Test #323: AreaTest.Bad ............................................Exit code 0xc0000139
***Exception:   0.01 sec
        Start 324: FramedAreaTest.Good
324/661 Test #324: FramedAreaTest.Good .....................................Exit code 0xc0000139
***Exception:   0.01 sec
        Start 325: FramedAreaTest.Bad
325/661 Test #325: FramedAreaTest.Bad ......................................Exit code 0xc0000139
***Exception:   0.01 sec
...
	322 - AreaTest.Good (Exit code 0xc0000139)
	323 - AreaTest.Bad (Exit code 0xc0000139)
	324 - FramedAreaTest.Good (Exit code 0xc0000139)
	325 - FramedAreaTest.Bad (Exit code 0xc0000139)

原因：需要静态链接C和C++标准库

解决方法：增加链接选项-static -static-libgcc -static-libstdc++

参考：https://stackoverflow.com/questions/4702732/the-program-cant-start-because-libgcc-s-dw2-1-dll-is-missing

Release模式下测试fibonacci_series_test运行失败

PR #12 尝试将CI使用的构建模式改为Release，但是运行测试时发现build-unix-makefiles (ubuntu-latest)和build-mingw-makefiles两个job在卡在运行测试fibonacci_series_test，导致超时失败：

定位原因后发现fibonacci_series依赖整数溢出结束循环，而这是一个未定义行为，参考Arithmetic operators - Overflows：

When signed integer arithmetic operation overflows (the result does not fit in the result type), the behavior is undefined

不同编译器、不同优化模式可能会有不同的结果。

在Linux系统、GCC 8.2.0、C++14环境下，使用下面的代码进行测试：

#include <iostream>

using namespace std;

int main() {
    int x = 1134903170, y = 1836311903, z = x + y;
    cout << z << ' ' << (z > 0) << endl;

    int a = 1, b = 1, i = 0;
    while (a > 0 && ++i < 50) {
        cout << a << ' ' << (a > 0) << endl;
        int c = a + b;
        a = b;
        b = c;
    }
    return 0;
}

Debug模式的输出结果：

-1323752223 0
1 1
1 1
2 1
3 1
...
701408733 1
1134903170 1
1836311903 1

Release模式的输出结果：

-1323752223 0
1 1
1 1
2 1
3 1
...
701408733 1
1134903170 1
1836311903 1
-1323752223 1
512559680 1
-811192543 1

可以看到，在Release模式下，当a发生溢出时，a > 0仍然被判断为true（甚至与循环之前z > 0的结果不同），因此导致无限循环。

GUI程序在macOS上编译失败

错误信息：

[ 94%] Linking CXX executable hello_fltk.app/Contents/MacOS/hello_fltk
Undefined symbols for architecture x86_64:
  "_CFAbsoluteTimeGetCurrent", referenced from:
      Fl::add_timeout(double, void (*)(void*), void*) in libfltk.a(Fl_cocoa.mm.o)
      Fl::repeat_timeout(double, void (*)(void*), void*) in libfltk.a(Fl_cocoa.mm.o)
      ...
  "_objc_retain", referenced from:
      Fl_X::set_cursor(Fl_Cursor) in libfltk.a(Fl_cocoa.mm.o)
      Fl_Paged_Device::print_window(Fl_Window*, int, int) in libfltk.a(Fl_cocoa.mm.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [ch12/hello_fltk.app/Contents/MacOS/hello_fltk] Error 1
make[1]: *** [ch12/CMakeFiles/hello_fltk.dir/all] Error 2
make: *** [all] Error 2

原因：缺少链接选项 -framework Cocoa