Does migrating code from vb.net to a C++ dll offer significant performance boosts?

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• Are there alternative and portable algorithm implementation for reading lines from a file on Windows (Visual Studio Compiler) and Linux?

  Right now I am doing this with C++ 11:

  long long int linecount;
  fileifstream.open( filepath );
  
  if( std::getline( fileifstream, newline ) ) 
  {
      linecount += 1;
      // do some stuff with line and throw it out
  }
  
  fileifstream.close();
  

  I would try to use this C getline() but it is not available under Windows (Visual Studio cl.exe compiler):

  FILE * ifile = fopen( filename, "r" );
  size_t linesz = 0;
  char * line = nullptr;
  unsigned int linecount = 0;
  
  while( getline( &line, &linesz, ifile ) > 0 ) 
  {
      linecount++;
      // do some stuff with line and throw it out
  }
  
  free( line );
  std::cout << "Lines count: " << linecount << std::endl;
  fclose(ifile);
  

  Can lines from a file being read faster (i.e., in less time using another implementation other than these standard ones) while reading/processing each line individually without having to load the whole file into memory at one (you assume a 10GB data file on a computer with 8GB of RAM)?

  Is there a known limit for the file's maximum size?

  No, the file can have either 1MB, or 40GB. The whole file does not have to be in memory, just a single line. But you can read more than just one line, caching like 1GB more.

  if there are N CPUs you want to be able to process "up to N" pieces of the file in parallel, while the next N pieces of the file are being read.

  I would assume just a single thread because the file needs to be parsed by lines and to synchronize all these threads to not get in the middle of each other should not be easy and would require a real complex implementation

  Also note that for max. performance (especially when the file is already cached by the OS in RAM, or is on a fast SSD);

  The file is not cached on RAM. The RAM is free and the file needs to come from the file system and be parsed by lines.

  Related:

  1. https://codereview.stackexchange.com/questions/115744/c-stack-implementation-using-stdlist
  2. std::ifstream in binary mode and locale in C++
  3. https://codereview.stackexchange.com/questions/119219/c-getline-implementation
  4. Performance difference of getline operating with istream and FILE*
• Array as value in ValueSet

  My goal is to add array of strings as value into ValueSet. I can do it in C# without any problem, but facing some problems in C++-WinRT.

  I am trying to pass array_view to box_value in order to convert it to IInspectable type, but getting error T must be WinRT type. Here is sample code to check the problem:

  ValueSet MyValueSet;
  hstring key(L"key");
  vector<wstring> mystringvalues{ L"1",L"2" };
  std::vector<hstring> hvector;
  for (std::wstring v : mystringvalues) {
      hvector.push_back(hstring(v));
  }
  array_view<hstring> hvalue(hvector);
  IInspectable keyValue = box_value(hvalue);
  MyValueSet.Insert(key, keyValue);
  

  Please advise how can I achieve this.
• How to refine image with rough horizontal lines using OpenCV?

  I have this kind of image that has rough horizontal lines and I want to remove it or at least make those lines not really visible.

  

  Using smoothing technique such as Gaussian Blur, I couldn't get satisfying result as the lines still visible and it just make resolution of the image lower.

  cv::GaussianBlur(image, result, cv::Size(5, 5), 3);
  

  

  Is there any other method that is more suitable for my problem? Thank you
• Get value from the same row with button click, Gridview

  So what I'm trying to do is I want to store the id in session when the button in the same row got clicked. No error but the the data doesn't seem to be stored in the session either. One thing for sure is the cell is neither empty or null. below is my code behind.

  Protected Sub dtGrid_RowCommand(sender As Object, e As GridViewCommandEventArgs) Handles dtGrid.RowCommand
      'Dim data As String = dtGrid.SelectedRow(0).Cells(5).Value.ToString
  
      If e.CommandName = "Go" Then
          'Determine the RowIndex of the Row whose Button was clicked.
          Dim rowIndex As Integer = Convert.ToInt32(e.CommandArgument)
  
          'Reference the GridView Row.
          Dim row As GridViewRow = dtGrid.Rows(rowIndex)
  
          'Fetch value of Name.
          'Fetch value of Country.
          Dim hsid As String = row.Cells(1).Text
          Session("hsid") = hsid
  
      End If
  End Sub
  

  Front end:

  <asp:GridView ID="dtGrid" runat="server" AllowPaging="True" AutoGenerateColumns="False" CssClass="table table-responsive table-striped  table-bordered table-sm" DataKeyNames="HSID" Width="100%" AllowSorting="True">
  <Columns>
  
      <asp:TemplateField ShowHeader="False">
          <ItemTemplate>
              <asp:Button ID="btnGO" runat="server" CausesValidation="false" CommandName="Go" Text="GO" CommandArgument='<%# Container.DataItemIndex %>' OnClientClick="window.location.href='form1.aspx'; return false;" class="btn btn-success" />
  
          </ItemTemplate>
      </asp:TemplateField>
      <asp:BoundField DataField="HSID" HeaderText="HSID" InsertVisible="False" ReadOnly="True" SortExpression="HSID" />
      <asp:BoundField DataField="PROCESS" HeaderText="PROCESS" SortExpression="PROCESS" />
      <asp:BoundField DataField="Criticality" HeaderText="Criticality" SortExpression="Criticality" />
      <asp:BoundField DataField="Date_Issued" HeaderText="Date_Issued" SortExpression="Date_Issued" />
      <asp:BoundField DataField="Due_Date" HeaderText="Due_Date" SortExpression="Due_Date" />
  </Columns>
  <HeaderStyle CssClass=" thead-dark" />
  

  The value that I'expect to get and store in the session is from the column HSID. Is there anything that I do wrong with my code ?
• rdlc report shows blank when multi-valued-parameter is set

  I'm trying to display field values in comma separated using multi valued report parameter with below expression, but report itself is showing blank.

  ="all values" & JOIN(Parameters!ReportParameter2.Label)
  

  ---

  I've dataset named 'Sessions' having fields as below -

  Id, typeof(int)
  MeetingId, typeof(int)
  SessionType, typeof(string)    
  

  ---

  I created multi valued report parameter in RDLC as below -
  General:
  Name: ReportParameter2
  Data type : Text
  Allow multiple values: checked
  

  Available values:
  Get values from a query : radio button checked
  Dataset: Sessions
  Value field: Id
  Label field: SessionType
  

  Default values:
  Get values from a query : radio button checked
  Dataset: Sessions
  Value field: Id
  

  ---

  My code in .aspx.cs, button click event as follows -

  DataTable table = new DataTable();
  table.Columns.Add("Id", typeof(int));
  table.Columns.Add("MeetingId", typeof(int));
  table.Columns.Add("SessionType", typeof(string));
  
  table.Rows.Add(1, 1, "case1");
  table.Rows.Add(2, 1, "case2");
  
  datasource = new ReportDataSource("Sessions", table);
  ReportViewer1.LocalReport.DataSources.Add(datasource);
  

  ---

  My code in .aspx, as follows -

  <%@ Register assembly="Microsoft.ReportViewer.WebForms, Version=15.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" 
  namespace="Microsoft.Reporting.WebForms" tagprefix="rsweb" %>
  <form id="form1" runat="server">
  
  <asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
  
  <rsweb:ReportViewer ID="ReportViewer1" runat="server" AsyncRendering="true"
      Style="width:100%;height:700px;"
      OnReportError="ReportViewer1_ReportError"></rsweb:ReportViewer>  
  
  <asp:Button OnClick="CaseList_Click" ID="Button2" runat="server" Text="CaseList" />
  
  </form>
  

  From last 2 days I'm working on this issue, please help me..
• How to declare a path without the drive letter?

  Example i have picture folder located at

  Dim path As String = "D:\Student Picture\Student-" + textbox_Search.Text + ".jpg"
  

  Something like that. now i want the the picture folder to just paste it in debug folder can i call it without the drive letter something like this ??

  Dim path As String = "\bin\debug\Student Picture\Student-" + textbox_Search.Text + ".jpg"
  

  Its not working. The reason why i want to achieve this is example i use my program in another computer but the other computer don't have drive D: then my program will not work because in my code all of the student picture declared in drive D: thank you so much.
• What is the most lag-free way of moving back X frames in a video/animation on a webpage?

  I'm putting my thesis presentation online, as a video with custom controls for going forward (similar to a powerpoint) between "slides" of an animated video. Some transitions between two "slides" need to repeat in a ~1 second loop, and the repeating part is where the lag happens.

  This is the only solution I've tried, since I don't have the time (the presentation is on Friday) nor the expertise needed to know what other video/animated image formats work well. I'm going to play around with different file formats (ogg, webm) to see if that makes a difference.

  Live website with thesis presentation.

  <html>
  <head>
  </head>
  <body>
      <video
          id="video-active"
          width="640"
          height="390"
          controls="">
          <source src="presentation.mp4" type="video/mp4">
      </video>
  </body>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js"></script>
  <script>
      video = document.querySelector("#video-active");
      framerate = 60;
      thresholdFrameNo = 300;
      timeToRevert = 0.5;
  
      $(document).ready(function(){
          document.querySelector("#video-active").defaultPlaybackRate = 1.0;
      $("#video-active").on(
      "timeupdate", 
      function(event){
        onTrackedVideoFrame(this.currentTime, this.duration);
      })});
  
      function onTrackedVideoFrame(currentTime, duration){
          currentFrame = Math.round(currentTime*framerate);
          if(currentFrame > thresholdFrameNo){
              video.currentTime -= timeToRevert;
          }
      }
  </script>
  </html>
  

  I expect the video to go to the position half a second earlier really fast, but it freezes for a bit (maybe up to half a second) at the old seek position, before playing.
• How do I speed up a double for loop with if in the inner loop in vba?

  I've written this code to search a match in a column of sheet "q1" with the elements of another column in sheet "Complete Car". Since I have 3000 rows to check in Complete Car and 1500 in q1 (inner loop), is there any suggestion on how to write this more efficiently?

  Code is below:

  Sub PopulateData()
  
   Sheets("Q1").Visible = True
  
    Dim i As Integer
    Dim j As Integer
  
    For i = 4 To 3000
  
          For j = 2 To 1500
  
  
          If Worksheets("Complete Car").Cells(i, 2) = Worksheets("Q1").Cells(j, 21) Then
  
             Worksheets("Complete Car").Cells(i, 32) = Worksheets("Q1").Cells(j, 30)
  
             End If
  
          Next j
  
    Next i
  
  
    Sheets("Q1").Visible = False
  
• Linking error when defining a function in a class

  I am writing an event system for a small game engine (called Turbo) I am currently working on. I have a class called "KeyEvent" which inherits from Event and "KeyPressedEvent" which inherits from KeyEvent. When I define the constructor for the classes inside of the classes, I get a linking error, but I do not get one, if the function declaration and definition are seperated:

  This code DOES work:

  #pragma once
  #include "Turbo/Core.h"
  #include "Turbo/Events/Event.h"
  
  namespace Turbo
  {
    class TURBO_API KeyEvent : public Event
    {
    protected:
      int m_keyCode;
  
      KeyEvent(int keyCode);
    };
  
    class TURBO_API KeyPressedEvent : public KeyEvent
    {
    public:
      KeyPressedEvent(int keyCode);
    };
  
    KeyEvent::KeyEvent(int keyCode) : m_keyCode(keyCode) {}
    KeyPressedEvent::KeyPressedEvent(int keyCode) : KeyEvent(keyCode) {}
  }
  

  This code DOES NOT work:

  #pragma once
  #include "Turbo/Core.h"
  #include "Turbo/Events/Event.h"
  
  namespace Turbo
  {
    class TURBO_API KeyEvent : public Event
    {
    protected:
      int m_keyCode;
  
      KeyEvent(int keyCode) : m_keyCode(keyCode) {}
    };
  
  
    class TURBO_API KeyPressedEvent : public KeyEvent
    {
    public:
      KeyPressedEvent(int keyCode) : KeyEvent(keyCode) {}
    };
  }
  

  (The Event class is currently empty)

  The macro "TURBO_API" is either __declspec(dllexport) for when the engine DLL is being build and __declspec(dllimport) when it is imported by another project. I only get the linking error in my "Sandbox" project (which imports the DLL)

  I try to initialize a KeyPressed event:

  Turbo::KeyPressedEvent e(8);
  

  But I get this error:

  1>Sandbox.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl Turbo::KeyPressedEvent::KeyPressedEvent(int)" (__imp_??0KeyPressedEvent@Turbo@@QEAA@H@Z) referenced in function main
  

  I made also sure that I include everything for the Sandbox project.

  I just want to know why it works using the first way but not the second.
• Libcurl function curl_easy_perform never returns when performing POST request

  I compiled libcurl 7.64.1 like a static library and I linked to a DLL of mine, both I built using Visual Studio 2017, Windows 10 Pro x64.

  I am following this example https://curl.haxx.se/libcurl/c/http-post.html trying to perform POST request by my DLL to an URL that recives POST perfectly when I try with POSTMAN.

  But with the libcurl the function curl_easy_perform never returns, it stays in there forever.

  /* Perform the request, res will get the return code */ 
  res = curl_easy_perform(curl);
  

  To compile libcurl I used this: nmake /f Makefile.vc mode=static RTLIBCFG=static

  I found this thread that reports the same problem, but with no solution. https://github.com/curl/curl/issues/2761
• How to solve 0xc000007b error in Watch Dogs

  How to solve the 0xc000007b error in Watch Dogs (open dll file)

  Generally, 0xc000007b is going on when some critical dll libraries are absent on the PC

  The application was unfit to begin accurately (0xc000007b). Snap alright to close the application". Well, we are here to help, so how about we get rapidly to the arrangement part of the 0xc000007b mistake in Watch Dogs.