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Modernize C# code snippets - System/D* #12948

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23dc2c8
Modernize C# code snippets
gewarren Aug 6, 2026
c0f2ab3
Apply suggestions from code review
gewarren Aug 7, 2026
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118 changes: 59 additions & 59 deletions snippets/csharp/System/DBNull/Overview/DBNullExamples.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,68 +6,68 @@ public class DBNullExample
{
public static void Main()
{
DBNullExample ex = new DBNullExample();
OleDbConnection conn = new OleDbConnection();
OleDbCommand cmd = new OleDbCommand();
OleDbDataAdapter adapter = new OleDbDataAdapter();
DataSet ds = new DataSet();
string dbFilename = @"c:\Data\contacts.mdb";
DBNullExample ex = new();
OleDbConnection conn = new OleDbConnection();
OleDbCommand cmd = new OleDbCommand();
OleDbDataAdapter adapter = new OleDbDataAdapter();
DataSet ds = new();
string dbFilename = @"c:\Data\contacts.mdb";

// Open database connection
conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" +
dbFilename + ";";
conn.Open();
// Define command : retrieve all records in contact table
cmd.CommandText = "SELECT * FROM Contact";
cmd.Connection = conn;
adapter.SelectCommand = cmd;
// Fill dataset
ds.Clear();
adapter.Fill(ds, "Contact");
// Close connection
conn.Close();
// Output labels to console
ex.OutputLabels(ds.Tables["Contact"]);
}
// Open database connection
conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" +
dbFilename + ";";
conn.Open();
// Define command : retrieve all records in contact table
cmd.CommandText = "SELECT * FROM Contact";
cmd.Connection = conn;
adapter.SelectCommand = cmd;
// Fill dataset
ds.Clear();
adapter.Fill(ds, "Contact");
// Close connection
conn.Close();
// Output labels to console
ex.OutputLabels(ds.Tables["Contact"]);
}

// <Snippet1>
private void OutputLabels(DataTable dt)
{
string label;
// <Snippet1>
private void OutputLabels(DataTable dt)
{
string label;

// Iterate rows of table
foreach (DataRow row in dt.Rows)
{
int labelLen;
label = String.Empty;
label += AddFieldValue(label, row, "Title");
label += AddFieldValue(label, row, "FirstName");
label += AddFieldValue(label, row, "MiddleInitial");
label += AddFieldValue(label, row, "LastName");
label += AddFieldValue(label, row, "Suffix");
label += "\n";
label += AddFieldValue(label, row, "Address1");
label += AddFieldValue(label, row, "AptNo");
label += "\n";
labelLen = label.Length;
label += AddFieldValue(label, row, "Address2");
if (label.Length != labelLen)
// Iterate rows of table
foreach (DataRow row in dt.Rows)
{
int labelLen;
label = string.Empty;
label += AddFieldValue(label, row, "Title");
label += AddFieldValue(label, row, "FirstName");
label += AddFieldValue(label, row, "MiddleInitial");
label += AddFieldValue(label, row, "LastName");
label += AddFieldValue(label, row, "Suffix");
label += "\n";
label += AddFieldValue(label, row, "Address1");
label += AddFieldValue(label, row, "AptNo");
label += "\n";
label += AddFieldValue(label, row, "City");
label += AddFieldValue(label, row, "State");
label += AddFieldValue(label, row, "Zip");
Console.WriteLine(label);
Console.WriteLine();
}
}
labelLen = label.Length;
label += AddFieldValue(label, row, "Address2");
if (label.Length != labelLen)
label += "\n";
label += AddFieldValue(label, row, "City");
label += AddFieldValue(label, row, "State");
label += AddFieldValue(label, row, "Zip");
Console.WriteLine(label);
Console.WriteLine();
}
}

private string AddFieldValue(string label, DataRow row,
string fieldName)
{
if (!DBNull.Value.Equals(row[fieldName]))
return (string) row[fieldName] + " ";
else
return String.Empty;
}
// </Snippet1>
private string AddFieldValue(string label, DataRow row,
string fieldName)
{
if (!DBNull.Value.Equals(row[fieldName]))
return (string)row[fieldName] + " ";
else
return string.Empty;
}
// </Snippet1>
}
116 changes: 58 additions & 58 deletions snippets/csharp/System/DateTime/.ctor/ctorexample1.cs
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Original file line number Diff line number Diff line change
@@ -1,68 +1,68 @@
using System;

public class Example
{
public static void Main()
{
ShowYMD();
Console.WriteLine("-----");
ShowYMDHMS();
Console.WriteLine("-----");
ShowYMDHMSMs();
Console.WriteLine("-----");
ShowYMDHMSKind();
Console.WriteLine("-----");
ShowYMDHMSMsKind();
public static void Main()
{
ShowYMD();
Console.WriteLine("-----");
ShowYMDHMS();
Console.WriteLine("-----");
ShowYMDHMSMs();
Console.WriteLine("-----");
ShowYMDHMSKind();
Console.WriteLine("-----");
ShowYMDHMSMsKind();

void ShowYMD()
{
// <Snippet1>
DateTime date1 = new DateTime(2010, 8, 18);
Console.WriteLine(date1.ToString());
// The example displays the following output:
// 8/18/2010 12:00:00 AM
// </Snippet1>
}
void ShowYMD()
{
// <Snippet1>
DateTime date1 = new(2010, 8, 18);
Console.WriteLine(date1.ToString());
// The example displays the following output:
// 8/18/2010 12:00:00 AM
// </Snippet1>
}

void ShowYMDHMS()
{
// <Snippet3>
DateTime date1 = new DateTime(2010, 8, 18, 16, 32, 0);
Console.WriteLine(date1.ToString());
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:00 PM
// </Snippet3>
}
void ShowYMDHMS()
{
// <Snippet3>
DateTime date1 = new(2010, 8, 18, 16, 32, 0);
Console.WriteLine(date1.ToString());
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:00 PM
// </Snippet3>
}

void ShowYMDHMSMs()
{
// <Snippet5>
DateTime date1 = new DateTime(2010, 8, 18, 16, 32, 18, 500);
Console.WriteLine(date1.ToString("M/dd/yyyy h:mm:ss.fff tt"));
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:18.500 PM
// </Snippet5>
}
void ShowYMDHMSMs()
{
// <Snippet5>
DateTime date1 = new(2010, 8, 18, 16, 32, 18, 500);
Console.WriteLine(date1.ToString("M/dd/yyyy h:mm:ss.fff tt"));
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:18.500 PM
// </Snippet5>
}

void ShowYMDHMSKind()
{
// <Snippet7>
DateTime date1 = new DateTime(2010, 8, 18, 16, 32, 0, DateTimeKind.Local);
Console.WriteLine("{0} {1}", date1, date1.Kind);
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:00 PM Local
// </Snippet7>
}
void ShowYMDHMSKind()
{
// <Snippet7>
DateTime date1 = new(2010, 8, 18, 16, 32, 0, DateTimeKind.Local);
Console.WriteLine($"{date1} {date1.Kind}");
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:00 PM Local
// </Snippet7>
}

void ShowYMDHMSMsKind()
{
// <Snippet8>
DateTime date1 = new DateTime(2010, 8, 18, 16, 32, 18, 500,
DateTimeKind.Local);
Console.WriteLine("{0:M/dd/yyyy h:mm:ss.fff tt} {1}", date1, date1.Kind);
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:18.500 PM Local
// </Snippet8>
}
}
void ShowYMDHMSMsKind()
{
// <Snippet8>
DateTime date1 = new(2010, 8, 18, 16, 32, 18, 500,
DateTimeKind.Local);
Console.WriteLine($"{date1:M/dd/yyyy h:mm:ss.fff tt} {date1.Kind}");
// The example displays the following output, in this case for en-us culture:
// 8/18/2010 4:32:18.500 PM Local
// </Snippet8>
}
}
}
63 changes: 27 additions & 36 deletions snippets/csharp/System/DateTime/.ctor/ctorexample2.cs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,3 @@
// <Snippet2>
using System;
using System.Globalization;
Expand All @@ -6,46 +6,37 @@

public class Example
{
public static void Main()
{
Console.WriteLine("Using the Persian Calendar:");
PersianCalendar persian = new PersianCalendar();
DateTime date1 = new DateTime(1389, 5, 27, persian);
Console.WriteLine(date1.ToString());
Console.WriteLine("{0}/{1}/{2}\n", persian.GetMonth(date1),
persian.GetDayOfMonth(date1),
persian.GetYear(date1));
public static void Main()
{
Console.WriteLine("Using the Persian Calendar:");
PersianCalendar persian = new();
DateTime date1 = new(1389, 5, 27, persian);
Console.WriteLine(date1.ToString());
Console.WriteLine($"{persian.GetMonth(date1)}/{persian.GetDayOfMonth(date1)}/{persian.GetYear(date1)}\n");

Console.WriteLine("Using the Hijri Calendar:");
// Get current culture so it can later be restored.
CultureInfo dftCulture = Thread.CurrentThread.CurrentCulture;
Console.WriteLine("Using the Hijri Calendar:");
// Get current culture so it can later be restored.
CultureInfo dftCulture = Thread.CurrentThread.CurrentCulture;

// Define Hijri calendar.
HijriCalendar hijri = new HijriCalendar();
// Make ar-SY the current culture and Hijri the current calendar.
Thread.CurrentThread.CurrentCulture = new CultureInfo("ar-SY");
CultureInfo current = CultureInfo.CurrentCulture;
current.DateTimeFormat.Calendar = hijri;
string dFormat = current.DateTimeFormat.ShortDatePattern;
// Ensure year is displayed as four digits.
dFormat = Regex.Replace(dFormat, "/yy$", "/yyyy");
current.DateTimeFormat.ShortDatePattern = dFormat;
DateTime date2 = new DateTime(1431, 9, 9, hijri);
Console.WriteLine("{0} culture using the {1} calendar: {2:d}", current,
GetCalendarName(hijri), date2);
// Define Hijri calendar.
HijriCalendar hijri = new();
// Make ar-SY the current culture and Hijri the current calendar.
Thread.CurrentThread.CurrentCulture = new("ar-SY");
CultureInfo current = CultureInfo.CurrentCulture;
current.DateTimeFormat.Calendar = hijri;
string dFormat = current.DateTimeFormat.ShortDatePattern;
// Ensure year is displayed as four digits.
dFormat = Regex.Replace(dFormat, "/yy$", "/yyyy");
current.DateTimeFormat.ShortDatePattern = dFormat;
DateTime date2 = new(1431, 9, 9, hijri);
Console.WriteLine($"{current} culture using the {GetCalendarName(hijri)} calendar: {date2:d}");

// Restore previous culture.
Thread.CurrentThread.CurrentCulture = dftCulture;
Console.WriteLine("{0} culture using the {1} calendar: {2:d}",
CultureInfo.CurrentCulture,
GetCalendarName(CultureInfo.CurrentCulture.Calendar),
date2);
}
// Restore previous culture.
Thread.CurrentThread.CurrentCulture = dftCulture;
Console.WriteLine($"{CultureInfo.CurrentCulture} culture using the {GetCalendarName(CultureInfo.CurrentCulture.Calendar)} calendar: {date2:d}");
}

private static string GetCalendarName(Calendar cal)
{
return Regex.Match(cal.ToString(), "\\.(\\w+)Calendar").Groups[1].Value;
}
private static string GetCalendarName(Calendar cal) => Regex.Match(cal.ToString(), "\\.(\\w+)Calendar").Groups[1].Value;
}
// The example displays the following output:
// Using the Persian Calendar:
Expand Down
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