c++ - How to make .dll and call it from c#

c++ DLL cpp:

extern "C" __declspec( dllexport )
int math_add( int const d1, int const d2 ) {
    return d1 + d2;
}

Test c++ console app:

#include 

extern "C" __declspec( dllimport ) int math_add( int, int );

int main( int argc, char* argv[] )
{
    int i = math_add( 4, 5 );

    std::cout << '\n' << i << '\n';
    
    std::cout << "Press any key..";

    std::cin.get();

    return 0;
}

C# class:

using System.Runtime.InteropServices;

namespace test {
    public class PILib {

        [DllImport( "piMath.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int math_add( int _v1, int _v2);

    }
}

Calling in c#:

private void button1_Click( object sender, EventArgs e ) {
    int i = PILib.math_add( 3, 5 );

    MessageBox.Show( i.ToString() );
}

Output:

c# - How to call Min(), Max() on generic List

DateTime minStartTime = 
ListOfProcesesForKilling.Min( p => {        
  return p.StartTime;
} );
value += $"Min starttime: {minStartTime};";

c# - How to force JSON enum to save as TEXT instead of a NUMBER

This enum property:

public enum MinimizeActionEnum {
  NONE = 0,
  CLEAR = 1
}
    
public MinimizeActionEnum MinimizeAction { get; set; } = MinimizeActionEnum.NONE;

It is saved as INT by default:

"ReportParams": [
{
  "Name": "pProdId",
  "Description": "",
  "MinimizeAction": 0
},

With using that attribute:

[JsonConverter(typeof(JsonStringEnumConverter))]
public MinimizeActionEnum MinimizeAction { get; set; } = MinimizeActionEnum.NONE;

the enum value will be stored as TEXT:

"ReportParams": [
{
  "Name": "pProdId",
  "Description": "",
  "MinimizeAction": NONE
},

ssrs - How to make expression to get yesterday date

=DateAdd("d", -1, Today())

sql server - How to get detailed info about localdb

List of installed local DBs:

sqllocaldb i

Output:

MSSQLLocalDB

More details about selected:

sqllocaldb info MSSQLLocalDB

Output:

Name:               MSSQLLocalDB
Version:            15.0.4382.1
Shared name:
Owner:              domain\pirklj
Auto-create:        Yes
State:              Running
Last start time:    14.10.2025 14:36:27
Instance pipe name: np:\\.\pipe\LOCALDB#FF67DE7F\tsql\query

List of installed DBLocal versions:

sqllocaldb versions

Output:

Microsoft SQL Server 2016 (13.0.7037.1)
Microsoft SQL Server 2017 (14.0.3391.2)
Microsoft SQL Server 2019 (15.0.4382.1)
Microsoft SQL Server 2022 (16.0.1000.6)

Stopping and deleting of DBLocal instance, creating it with new higher version:

C:\Users\pirklj>sqllocaldb stop MSSQLLocalDB
LocalDB instance "MSSQLLocalDB" stopped.

C:\Users\pirklj>sqllocaldb delete MSSQLLocalDB
LocalDB instance "MSSQLLocalDB" deleted.

C:\Users\pirklj>sqllocaldb create MSSQLLocalDB
LocalDB instance "MSSQLLocalDB" created with version 16.0.1000.6.

C:\Users\pirklj>sqllocaldb start MSSQLLocalDB
LocalDB instance "MSSQLLocalDB" started.

c# - How to solve JSON deserialization problem

JSON deserialization returns this error:

Each parameter in the deserialization constructor on type 
'cieb_AXReportPrintDLG.ReportParamComboValues' must bind 
to an object property or field on deserialization. Each 
parameter name must match with a property or field on the 
object. Fields are only considered when 
'JsonSerializerOptions.IncludeFields' is enabled. 
The match can be case-insensitive.

All fields looks like OK. The problem is in the parameter names in the constructor. This version returns error:

public class ReportParamComboValues {

  /* description - for text */
  public string Description { get; set; }

  /* returned value for SSRS report param */
  public string Value { get; set; }

  public ReportParamComboValues( string _description, string _value ) {  
    this.Description = _description;
    this.Value = _value;
  }

}

This is working:

public class ReportParamComboValues {

  /* description - for text */
  public string Description { get; set; }

  /* returned value for SSRS report param */
  public string Value { get; set; }

  public ReportParamComboValues( string Description, string Value ) {  
    this.Description = Description;
    this.Value = Value;
  }

}

c# - How to solve problem with convension date into string with char "/" in format mask

This result can be obtained when trying to convert a date to a string using a format mask containing the character '/'.

DateTime dt = DateTime.Now;
MessageBox.Show( dt.ToString( "yyyy/MM/dd", CultureInfo.GetCultureInfo( "de-DE" ) ) );

Output:

2025.09.29

The solution is to change the Culture:

DateTime dt = DateTime.Now;
MessageBox.Show( dt.ToString( "yyyy/MM/dd", CultureInfo.GetCultureInfo( "en-US" ) ) );

Output:

2025/09/29

sql server - How to solve problem with CHARINDEX() - value subtraction

If you use this SQL code:

SUBSTRING( a.PackingSlipId, 1, CHARINDEX('-', a.PackingSlipId ) - 1 ) as document,

..you can get this error, even in a situation when CHARINDEX() returns valid values: Output:

Msg 537, Level 16, State 3, Line 1
Invalid length parameter passed to the LEFT or SUBSTRING function.

The solution is to use NULLIF() function:

SUBSTRING( a.PackingSlipId, 1, nullif( CHARINDEX('-', a.PackingSlipId ), 0 ) -1 ) as document,

ssrs - How to replace char with new row char

=Replace( Fields!Field.Value, ",", vbCrLf )

c# - How to add items to combobox with text description from attribute

Define new enum with attributes:

/* types for printing type combobox */
public enum PrintingTypeEnum
{
  [Description( "On screen" ) ]
  TO_SCREEN,
  [Description( "On printer" ) ]
  TO_PRINT
}

Fill the combobox with items:

CPrintingType.Items.Clear();
foreach (  PrintingTypeEnum item in Enum.GetValues( typeof( PrintingTypeEnum ) ) )
{
    string description = GetEnumDescription( item );
    CPrintingType.Items.Add( description );

    /* -- default value */  
    if ( item == PrintingTypeEnum.TO_PRINT )
    {
    	CPrintingType.SelectedIndex = CPrintingType.Items.Count - 1;
    }
}

private string GetEnumDescription( Enum _value )
{
    FieldInfo field = _value.GetType().GetField( _value.ToString() );
    DescriptionAttribute attribute = field?.GetCustomAttribute<DescriptionAttribute>();
    return attribute == null ? _value.ToString() : attribute.Description;
}

Output:

c# - EF - How to call storedproc with OUTPUT param

You have this stored proc:

ALTER PROCEDURE [dbo].[TEST]
	-- Add the parameters for the stored procedure here
( @Param1 int, @Message varchar(50) output )
AS
BEGIN
  set @Message = 'xxx';

  return '-1';
END

For calling it use this code:

var param1 = new SqlParameter( "Param1", System.Data.SqlDbType.Int );
param1.Direction = System.Data.ParameterDirection.Input;
param1.Value = iYear;

var message = new SqlParameter( "Message", System.Data.SqlDbType.VarChar, 50 ); 
message.Direction = System.Data.ParameterDirection.InputOutput;
message.Value = "";

var ret = context.Database.ExecuteSqlRaw(
  "EXEC TEST @Param1 = @param1, @Message = @message OUTPUT", param1, message
);

MessageBox.Show( message.Value.ToString() );
MessageBox.Show( ret.ToString() );

c# - EF - How to refresh existing DB into EF model

If you have DB and if you want to refresh it`s model into MODEL directory, call this:

dotnet ef dbcontext scaffold "Server=(LocalDB)\MSSQLLocalDB;
AttachDbFilename=C:\_projects\vs\FioTax\FioTax\db.mdf;
Integrated Security=True;Connect Timeout=30" Microsoft.EntityFrameworkCore.SqlServer 
--output-dir Models --context AppDbContext --force

sql server - How to run export script by sqlcmd

In command.sql is stored SQL select script, this calling performs it and save output to output.txt.

The param "-h -1" removes title row.

sqlcmd -S localhost\sqlexpress -d username -U sa -P password -h -1 -m 1 
-i "c:\dir\command.sql" -o "c:\dir\output\output.txt"

ax - How to check if the class is running in the batch mode ?

boolean bManualRunning = (BatchHeader::isExecutingInBatch() == false );