See also questions close to this topic

• How to return an enum by item index as apposed to value index?

  How do I index into an enum via "item index" instead of the "value indexing":

  "Value indexing" (not useful to me with what I am doing):

  eSerialBauds eBaud = static_cast<eSerialBauds>(1200); // yields eBaud1200
  

  I want "item indexing": ( How to get the following? )

  eSerialBauds eBaud = static_cast<eSerialBauds>(3); // to yield eBaud1200
  

  ---

  // values (from WinBase.h)
  #define CBR_110             110
  #define CBR_300             300
  #define CBR_600             600
  #define CBR_1200            1200
  #define CBR_2400            2400
  
  
  
  enum class eSerialBauds
  {
    eBaud110 = CBR_110,
    eBaud300 = CBR_300,
    eBaud600 = CBR_600,
    eBaud1200 = CBR_1200,
    eBaud2400 = CBR_2400,
  }
  

  ---

  Please note that I am given this enum class from another class. There are many. So I have to work with what is given to me.

  I did write a work around method but it would be nice to have a more elegant way of getting the result.
• I have a problem with a code c++ compiler lex and yacc

  and the error of code yacc code , conflicts: 9 reduce/reduce , What is the solution to this error? lex code:

  
      %option noyywrap
      %option yylineno
      %{
          #include<stdio.h>
          #include<string.h>
          #include "y.tab.h"
      FILE *out;
      %}
      
      %%
      
      "begin"|"print"|"end"|"while"|"endwhile"|"if"|"else"|"endif"|"read" {fprintf(out,"keyword :%s\n",yytext);}
      [A-Za-z][A-Za-z0-9_]+ {fprintf(out,"Identifier :%s\n",yytext);return ident;}
      "+" {fprintf(out,"plus :%s\n",yytext);}
      ":=" {fprintf(out,"assignsymbol :%s\n",yytext);}
      ";" {fprintf(out,"semicolon :%s\n",yytext);}
      [0-9]+ { fprintf(out,"number :%s\n",yytext); return number;}
      "(" {fprintf(out,"leftpar :%s\n",yytext);}
      ")" {fprintf(out,"righttpar :%s\n",yytext);}
      .|[\n]        {yylineno++;}
      %%
      int main()
      {
      yyin=fopen("read.txt","r");
      out=fopen("write.txt","w");
      yylex();
          return 0;
      }
  
  

  yacc code:

  
      %{
      #include <stdio.h>
      int yylex(void);
      void yyerror(char *);
      %}
      %start program
      %token number ident
      %right '='
      %left '+' '-'
      %left '*' '/'
      %%
      program: 
      "begin" stmt_list "end";
      stmt_list:
       stmt ';' 
       | stmt ';' stmt_list
       ;
      stmt:
       assign 
       | if_stmt
       | while_stmt "read" '(' ident ')'
       | "print" '(' ident ')'
       ;
      assign:
       ident ":=" expr
      expr:
       expr '+' term { $$ = $1 + $3; }
       | expr '-' term { $$ = $1 - $3; }
       | term { $$ = $1; }
       ;
      term:
       term '*' factor { $$ = $1 * $3; }
       | expr '/' term {
       if($3==0)
       yyerror([gdivide0پh]);
       else
       $$ = $1 / $3;
       }
       | factor { $$ = $1; }
       ;
      factor:
       ident { $$ = $1; }
       | number  { $$ = $1; }
       | '(' expr ')' { $$ = $2; }
       ;
      if_stmt:
       "if" '(' logic_expr ')' "then" stmt_list "endif"
       | "if" '(' logic_expr ')' "then" stmt_list "else" stmt_list "endif"
       ;
       while_stmt:
       "while" '(' logic_expr ')' stmt_list "endwhile"
       ;
      logic_expr:
       logic_term '>' logic_term
       |logic_term '<' logic_term
       |logic_term '>' '=' logic_term
       |logic_term '<' '=' logic_term
       |logic_term '<' '>' logic_term
       |logic_term '=' logic_term { $$ = $1 ; }
       ;
      logic_term:
       number { $$ = $1; }
       | ident { $$ = $1; }
       | '(' logic_expr ')'
       ;
      %%
      void yyerror(char *s) {
          fprintf(stderr, ""At line %d %s "", yylineno, s);
      }
      int main(void) {
       yyparse();
       return 0;
      }
  
  
• I want it to close when it opens the exe file separately

  I have two exe files coded in C# and C++. What I want to do is to download and run the exe coded with C++ from C#. When the C++ application is not brought from the C# application, I do not want it to be launched directly from the downloaded folder. How can I do this?
• Is there a way to inject the Azure DevOps buildId into a Vue.js build?

  Right now I am using a version number on my vue app frontend, which I manually write into package.json and then get it from there like this:

  // package.json
  {
      ...
      "version": "1.1.3",
      ...
  }
  

  // vue.config.js
  // ...
  process.env.VUE_APP_VERSION = require('./package.json').version
  

  // store/index.js
  state: {
      // ...
      appVersion: process.env.VUE_APP_VERSION || '0'
    },
  

  I was wondering if there is a way to inject an Azure DevOps buildId into a Vue build, so that I can display it directly on the web app frontend?
• Azure app service build and deploy failing on GitHub

  I just uploaded a very basic Xamarin mobile app to git hub. I used the azure option to set up a service to build and deploy. Unfortunately the GitHub build is failing in both the IOS and Android projects for the same error: Error:

  D:\a\MobileApplication\MobileApplication\MobileApplication\MobileApplication\Services\EventMockData.cs(65>,1): error CS1022: Type or namespace definition, or end-of-file expected >[D:\a\MobileApplication\MobileApplication\MobileApplication\MobileApplication\MobileApplication.csproj]

  I can't find anything wrong with the EventMockData.cs file. and the whole project builds successfully in my local VS.

  using MobileApplication.Models;
  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Net;
  using System.Text;
  using System.Threading.Tasks;
  
  namespace MobileApplication.Services
  {
      class EventMockData : IDataStore<Event>
      {
          readonly List<Event> events;
  
          public EventMockData()
          {
              events = new List<Event>()
              {
                  new Event { id = 1,
                      eventName = "Sunday School", 
                      eventContactName = "John",
                      eventContactEmail = "john@test.com",
                      eventContactPhone = 1234567890,
                      eventImageUrl = "https://wwww.dell.com",
                      eventStartDateTime = new DateTime(2021, 04, 30, 13, 00, 00), 
                      eventEndDateTime = new DateTime(2021, 04, 30, 20, 00, 00), 
                      eventRecurrance = "daily", 
                      eventRecurranceInterval = 1, 
                      eventRecurrenceDayInterval = ""}
              };
          }
          public async Task<bool> AddItemAsync(Event item)
          {
              events.Add(item);
  
              return await Task.FromResult(true);
          }
  
          public async Task<bool> UpdateItemAsync(Event item)
          {
              var oldItem = events.Where(e => e.id == item.id).FirstOrDefault(); 
              events.Remove(oldItem);
              events.Add(item);
  
              return await Task.FromResult(true);
          }
  
          public async Task<bool> DeleteItemAsync(int id)
          {
              var oldItem = events.Where((Event arg) => arg.id == id).FirstOrDefault();
              events.Remove(oldItem);
  
              return await Task.FromResult(true);
          }
  
          public async Task<Event> GetItemAsync(int id)
          {
              return await Task.FromResult(events.FirstOrDefault(s => s.id == id));
          }
  
          public async Task<IEnumerable<Event>> GetItemsAsync(bool forceRefresh = false)
          {
              return await Task.FromResult(events);
          }
      }
  }
  
  
• VSCode CMake Extension rebuild all project each time

  I'm working on a project in C++ configured using CMake.
  Each time I build the project, all files are recompiled, which is unbearable considering the time it takes.

  With Visual Studio Code

  I'm trying to use VSCode and the CMake Extension.
  The CMake:Configure command works well and so does the CMake:Build command. It takes a lot of time to compile because I use highly templatized header-only libraries like Eigen3, Boost and CGAL, so I need to build a pre-compiled header. It build some librairies too. But it is normal that it takes time for a first compilation.

  However, if I build the target again (without modifying anything in the code) the compilation is completely redone ! I just want the modified source files or librairies to be re-compiled. Or if a header in the list of pre-compiled headers is modified, only then should the pre-compiled headers be recompiled.

  With Visual Studio 2019

  I thought that VSCode didn't work with a concept of "project", and therefore had to reconfigure and recompile the whole project every time it was launched.
  So I decided to generate a Visual Studio Solution with the CMake-GUI program and use Visual Studio 2019 instead of VSCode.
  Now when I build a second time my project, nothing is recompiled and the program is directly lauched. Visual Studio say :

  ========== Build: 0 succeeded, 0 failed, 5 up-to-date, 0 skipped ==========
  

  Wonderful!
  Unfortunately not..., because if I modify a file, Visual Studio keeps telling me that everything is up-to-date and my modifications are not taken into account. I need to "Rebuild" the project so that everything will be recompiled, which does not solve my problem as it takes a lot of time.

  Question

  How to recompile only modified source files, librairies or pre-compiled headers (with VS Code, Visual Studio or both) ?

  ---

  Plaform : Windows 10

  Edit 15.04.21

  I did some more methodical testing today to find out what the problem might be.
  I used a very simple project to do the tests.

  CMakeList.txt

  cmake_minimum_required (VERSION 3.8)
  project ("HelloCMake")
  add_executable (HelloCMake "HelloCMake.cpp")
  

  HelloCMake.cpp

  #include <iostream>
  int main() {
      std::cout << "Hello CMake !" << std::endl;
      return 0;
  }
  

  1. With VSCode and CMake Tools Extension

  With the CMake Tools Extension, VSCode can configure and build a CMake project. It generate a Visual Studio Solution (.sln).

  1. Build the target with CMake Tools Extension which makes VSCode to run the command :

     cmake --build <PROJECT_DIR>/build --config Release --target HelloCMake -- 
     /maxcpucount:14
     

  2. The entire target is compiled
  3. I build it again (without changes)
  4. The target is completely recompiled again

  The problem is that the target is completely recompiled, every time. I asked the question directly to the CMake Tools developers. GitHub Issue

  2. .sln project generated by CMake (Visual Studio 2019)

  1. I generated a Visual Studio Solution with CMake and open it.
  2. I build my project HelloCMake
  3. I do some modifications in source file
  4. I build the project again, but Visual Studio never takes my modifications into account. The builds are always "up-to-date".

  The problem is that Visual Studio does not take my changes into account. I have to rebuild the project, which takes too much time.

  3. Directly open CMake project with Visual Studio 2019 (Ninja)

  If you open a CMakeList.txt with Visual Studio 2019, it is not a Visual Studio Solution that is generated but a Ninja one.

  It seems that this way the compilation works correctly !

  According to this research, it is the CMake Tools Extension for VSCode as well as the Visual Studio Solution that cause problems.

  I can't figure out why such a simple project doesn't compile properly with a Visual Studio Solution generated by CMake.
• Is cygwin possible to install epoll.h on win10?

  I compile a linux network project with cygwin32 on win10.
  The reason for doing this is that I can use comfortable IDE coding envrionment and donot need switch to linux environment to do real-time compilation.
  Cygwin shows non-found file error.

  fatal error: sys/epoll.h: No such file or directory
      6 | #include <sys/epoll.h>
  

  Does this mean epoll is something only available in the linux 2.6 kernel? Cygwin has most but not all linux feature?
• Start cmd.exe from cygwin shell with original Windows environment variables?

  I cannot use vcvarsall.bat from cygwin because cygwin overwrites environment variables (like PATH) and then the environment in cmd.exe, which is inherited from the cygwin BASH environment, finds the wrong cmake.exe.

  Is there any pre-defined way to do this? Maybe without having to resort to opening a new shell window? Currently, I'm rewriting and stripping the entire PATH string. But now I have another issue: TEMP points to the wrong directory. I could just change that manually, but I really want it to adhere to original Windows behaviour.
• No Gearman worker available

  Hello everyone I am having issues starting an Gearman woker in Windows I keep on getting this error.

  500 | Internal Server Error | Net_Gearman_Exception No Gearman worker available that can handle the job arFileImportJob.

  I have the Gearmand Server running in cygwin64, and I already installed PECL with gearman.

  Thanks for the help
• Why is clang reporting an undefined symbol for an extern variable referenced in a static library

  I witnessed this error which is reproducible in AppleClang 12.0.0 but not with gcc 7.5.0. The issue is that I have an extern variable defined in a static library which a different static library wants to use. The linker states that the symbol for the variable is undefined. I tried to come up with an as minimal as possible repro:

  externs.h

  extern int A;
  

  a.c

  int A;
  

  b.h

  void bar();
  

  b.c

  #include "externs.h"
  
  #include <stdio.h>
  
  void bar()
  {
      A = 100;
      printf("%d\n", A);
  }
  

  main.c

  #include "b.h"
  
  int main()
  {
      bar();
  }
  

  makefile

  liba.a: a.c
      gcc -c a.c -o a.o
      ar crs liba.a a.o
  
  libb.a: b.c
      gcc -c b.c -o b.o
      ar crs libb.a b.o
  
  program: main.c liba.a libb.a
      gcc main.c -L. -lb -la -o program
  

  On Linux, this program compiles, links and runs without issue. On macOS (where gcc is AppleClang) I get the following output :

  gcc -c a.c -o a.o
  ar crs liba.a a.o
  warning: /Library/Developer/CommandLineTools/usr/bin/ranlib: archive library: liba.a the table of contents is empty (no object file members in the library define global symbols)
  gcc -c b.c -o b.o
  ar crs libb.a b.o
  gcc main.c -L. -lb -la -o program
  Undefined symbols for architecture x86_64:
    "_A", referenced from:
        _bar in libb.a(b.o)
  ld: symbol(s) not found for architecture x86_64
  

  AFAICT, the warning is a red herring. If I add a dummy function to a.c, the warning doesn't show. Further, if I inspect liba.a with nm I get the following output:

  liba.a(a.o):
  0000000000000004 C _A
  

  If I do add a dummy function foo (which doesn't even refer to A) to liba.a and invoke it from main.c, the linking issue gets magically resolved. It's as if if and only if main.o is dependent on a symbol in liba.a, then all the symbols of liba.a become available to anything that may be dependent on them.
• mingw32 gcc importing symbols from wrong library

  I'm trying to build a CPython extensions on Linux for Windows, using mingw64's cross-compiler.
  I've copied the include folder and lib file from a Windows distributions and compiled with the following command:
  x86_64-w64-mingw32-gcc extension.c -o extension.pyd -I py_38_win/include -L py_38_win -shared -fPIC -static -lpython38

  The compilation succeeds, but the DLL created, is trying to import all kernel32.dll symbols from python38.dll, which of course, doesn't have them, so it obviously fails to load.

  1. Any idea why this is happening? python38.lib isn't even exporting these symbols
  2. Any ideas on how I can troubleshoot this? Is there a linker flag to log the symbol resolution and maybe shed some light on this?

  extension.c:

  #include <Python.h>
  
  static PyObject * f(PyObject *self, PyObject *args)
  {
      printf("I am the extension\n");
      Py_RETURN_NONE;
  }
  
  static PyMethodDef _module_methods[] = {
      {"f", f, METH_VARARGS, NULL},
      {NULL, NULL, 0, NULL}
  };
      
  static struct PyModuleDef _mymodule = {
      PyModuleDef_HEAD_INIT,
      "extension",
      "an extension module",
      -1,
      _module_methods,
      NULL,
      NULL,
      NULL,
      NULL
  };
  
  PyMODINIT_FUNC PyInit_extension(void)
  {
      PyObject *m = PyModule_Create(&_mymodule);
      if (!m)
          return NULL;
  
      return m;
  }
  

  Here's the output of dumpbin /imports for the generated DLL:

  C:\>dumpbin.exe /imports extension.pyd
  Microsoft (R) COFF/PE Dumper Version 14.28.29335.0
  Copyright (C) Microsoft Corporation.  All rights reserved.
  
  
  Dump of file extension.pyd
  
  File Type: DLL
  
    Section contains the following imports:
  
      python38.dll
                693891C0 Import Address Table
                69389070 Import Name Table
                       0 time date stamp
                       0 Index of first forwarder reference
  
                           5FD _Py_NoneStruct
                           1FD PyModule_Create2
                           11B DeleteCriticalSection
                           13F EnterCriticalSection
                           228 GetCurrentProcess
                           229 GetCurrentProcessId
                           22D GetCurrentThreadId
                           276 GetLastError
                           301 GetSystemTimeAsFileTime
                           31F GetTickCount
                           37C InitializeCriticalSection
                           3D8 LeaveCriticalSection
                           46B QueryPerformanceCounter
                           4C6 RtlAddFunctionTable
                           4C7 RtlCaptureContext
                           4CE RtlLookupFunctionEntry
                           4D5 RtlVirtualUnwind
                           572 SetUnhandledExceptionFilter
                           582 Sleep
                           591 TerminateProcess
                           5A5 TlsGetValue
                           5B3 UnhandledExceptionFilter
                           5D4 VirtualProtect
                           5D6 VirtualQuery
  
      KERNEL32.dll
                693891D0 Import Address Table
                69389080 Import Name Table
                       0 time date stamp
                       0 Index of first forwarder reference
  
                           11B DeleteCriticalSection
                           13F EnterCriticalSection
                           228 GetCurrentProcess
                           229 GetCurrentProcessId
                           22D GetCurrentThreadId
                           276 GetLastError
                           301 GetSystemTimeAsFileTime
                           31F GetTickCount
                           37C InitializeCriticalSection
                           3D8 LeaveCriticalSection
                           46B QueryPerformanceCounter
                           4C6 RtlAddFunctionTable
                           4C7 RtlCaptureContext
                           4CE RtlLookupFunctionEntry
                           4D5 RtlVirtualUnwind
                           572 SetUnhandledExceptionFilter
                           582 Sleep
                           591 TerminateProcess
                           5A5 TlsGetValue
                           5B3 UnhandledExceptionFilter
                           5D4 VirtualProtect
                           5D6 VirtualQuery
  
      msvcrt.dll
                69389288 Import Address Table
                69389138 Import Name Table
                       0 time date stamp
                       0 Index of first forwarder reference
  
                            54 __iob_func
                            79 _amsg_exit
                           11E _initterm
                           184 _lock
                           2CB _unlock
                           386 abort
                           397 calloc
                           3BE free
                           3CA fwrite
                           40D puts
                           414 realloc
                           41E signal
                           433 strlen
                           436 strncmp
                           455 vfprintf
  
    Summary
  
          1000 .CRT
          1000 .bss
          1000 .data
          3000 .debug_abbrev
          1000 .debug_aranges
          1000 .debug_frame
         35000 .debug_info
          3000 .debug_line
          4000 .debug_loc
          1000 .debug_ranges
          1000 .debug_str
          1000 .edata
          1000 .idata
          1000 .pdata
          1000 .rdata
          1000 .reloc
          2000 .text
          1000 .tls
          1000 .xdata
  

  P.S. It works fine when I compile and run it on Linux:

  $ gcc -I /usr/include/python3.8 extension.c -o extension.so -shared -fPIC
  $ python -c "import extension;extension.f()"
  I am the extension
  
• Recipe for target rule and all C++ CLion Windows one file

  I am trying to run an SFML program in CLion. I keep getting an error:

  "C:\Program Files\JetBrains\CLion 2020.3.2\bin\cmake\win\bin\cmake.exe" --build C:\Users\filip\CLionProjects\SFML_try1\cmake-build-debug --target SFML_try1 -- -j 6
  mingw32-make.exe[3]: *** No rule to make target '/SFML/lib/sfml-system-d.lib', needed by 'SFML_try1.exe'.  Stop.
  mingw32-make.exe[2]: *** [CMakeFiles/SFML_try1.dir/all] Error 2
  mingw32-make.exe[1]: *** [CMakeFiles/SFML_try1.dir/rule] Error 2
  mingw32-make.exe: *** [SFML_try1] Error 2
  CMakeFiles\Makefile2:94: recipe for target 'CMakeFiles/SFML_try1.dir/all' failed
  CMakeFiles\Makefile2:101: recipe for target 'CMakeFiles/SFML_try1.dir/rule' failed
  Makefile:137: recipe for target 'SFML_try1' failed
  

  I don't know anything about CMake. I use Windows, CLion, MinGW32, SFML. I don't even know where to look to fix this problem so this is why I don't post any code.
• SFML Error 1 2 2, CMake failed build windows CLion

  I've been trying to set up a new SFML project and i always struggle with importing libraries. I thought that everything is fine but the errors say otherwise. Anyway, heres the code and error message:

  vvvv CMake vvvv

  cmake_minimum_required(VERSION 3.17)
  project(SFML_try1)
  
  set(CMAKE_CXX_STANDARD 14)
  
  add_executable(SFML_try1 main.cpp)
  
  include_directories(C:/SFML/include)
  set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake_modules")
  find_package(SFML REQUIRED system window graphics)
  if(SFML_FOUND)
      include_directories(${SFML_INCLUDE_DIR})
      target_link_libraries(SFML_try1 ${SFML_LIBRARIES})
  endif()
  
  file(COPY assets DESTINATION ${CMAKE_BINARY_DIR})
  
  if(WIN32)
      file(GLOB BINARY_DEP_DLLS "${SFML_INCLUDE_DIR}/../bin/*.dll")
      file(COPY ${BINARY_DEP_DLLS} DESTINATION ${CMAKE_BINARY_DIR})
  endif()
  

  vvvv main.cpp vvvv

  #include <iostream>
  #include <SFML/Graphics.hpp>
  #include <SFML/System.hpp>
  #include <SFML/Window.hpp>
  
  using namespace sf;    
  int main()
  {
      RenderWindow window(VideoMode(640, 480), "screen", Style::Titlebar | Style::Close);
      Event ev;
  
      while(window.isOpen())
      {
          while(window.pollEvent(ev))
          {
              switch(ev.type)
              {
                  case Event::Closed:
                      window.close();
                      break;
                  case Event::KeyPressed:
                      if(ev.key.code == Keyboard::Escape)
                          window.close();
                      break;
                  default:
                      break;
              }
          }
          window.clear();
          window.display();
      }
  
      return 0;
  }
  

  vvvv error message vvvv

  "C:\Program Files\JetBrains\CLion 2020.3.2\bin\cmake\win\bin\cmake.exe" 
  
  --build C:\Users\filip\CLionProjects\SFML_try1\cmake-build-debug --target SFML_try1 -- -j 6
  mingw32-make.exe[3]: *** No rule to make target '/SFML/lib/sfml-system-d.lib', needed by 'SFML_try1.exe'.  Stop.
  mingw32-make.exe[2]: *** [CMakeFiles/SFML_try1.dir/all] Error 2
  mingw32-make.exe[1]: *** [CMakeFiles/SFML_try1.dir/rule] Error 2
  mingw32-make.exe: *** [SFML_try1] Error 2
  CMakeFiles\Makefile2:94: recipe for target 'CMakeFiles/SFML_try1.dir/all' failed
  CMakeFiles\Makefile2:101: recipe for target 'CMakeFiles/SFML_try1.dir/rule' failed
  Makefile:137: recipe for target 'SFML_try1' failed
  

  FindSFML.cmake is located inside cmake_modules in SFML_try1 folder

  I use minGW toolchain located on C drive

  main SFML folder is located on C drive

  I use CLion which comes with CMake pre-installed
• CLion run and makefile showing different results

  I have this C++ program in Clion, however, I need to create a makefile for it to be run on text editors and not IDEs, it is for a university, they do not use IDEs.

  When I run my program trough the run button on CLion, it works perfectly but when I run it trough the makefile, it displays multiple errors that don't even make sense.

  When is the issue occurring from? Please tell me if you need more information or images.

  Project structure:

  

  Errors with makefile:

  

  Run without the makefile:

  

  Makefile:

  OBJS    = main.o HastTable.o Book.o
  SOURCE  = main.cpp HastTable.cpp Book.cpp
  HEADER  = HashTable.h Book.h
  OUT = book
  CC   = g++
  FLAGS    = -g -c -Wall -Wextra
  
  all: $(OBJS)
      $(CC) -g $(OBJS) -o $(OUT) $(LFLAGS)
  
  main.o: main.cpp
      $(CC) $(FLAGS) main.cpp
  
  HastTable.o: HastTable.cpp
      $(CC) $(FLAGS) HastTable.cpp
  
  Book.o: Book.cpp
      $(CC) $(FLAGS) Book.cpp
  
  
  clean:
      rm -f $(OBJS) $(OUT)