I'm looking for some succinct, modern C# code to generate a random date between Jan 1 1995 and the current date.
I'm thinking some solution that utilizes Enumerable.Range somehow may make this more succinct.
private Random gen = new Random();
DateTime RandomDay()
{
DateTime start = new DateTime(1995, 1, 1);
int range = (DateTime.Today - start).Days;
return start.AddDays(gen.Next(range));
}
For better performance if this will be called repeatedly, create the start and gen (and maybe even range) variables outside of the function.
This is in slight response to Joel's comment about making a slighly more optimized version. Instead of returning a random date directly, why not return a generator function which can be called repeatedly to create a random date.
Func<DateTime> RandomDayFunc()
{
DateTime start = new DateTime(1995, 1, 1);
Random gen = new Random();
int range = ((TimeSpan)(DateTime.Today - start)).Days;
return () => start.AddDays(gen.Next(range));
}
I have taken #Joel Coehoorn answer and made the changes he adviced - put the variable out of the method and put all in class. Plus now the time is random too. Here is the result.
class RandomDateTime
{
DateTime start;
Random gen;
int range;
public RandomDateTime()
{
start = new DateTime(1995, 1, 1);
gen = new Random();
range = (DateTime.Today - start).Days;
}
public DateTime Next()
{
return start.AddDays(gen.Next(range)).AddHours(gen.Next(0,24)).AddMinutes(gen.Next(0,60)).AddSeconds(gen.Next(0,60));
}
}
And example how to use to write 100 random DateTimes to console:
RandomDateTime date = new RandomDateTime();
for (int i = 0; i < 100; i++)
{
Console.WriteLine(date.Next());
}
Well, if you gonna present alternate optimization, we can also go for an iterator:
static IEnumerable<DateTime> RandomDay()
{
DateTime start = new DateTime(1995, 1, 1);
Random gen = new Random();
int range = ((TimeSpan)(DateTime.Today - start)).Days;
while (true)
yield return start.AddDays(gen.Next(range));
}
you could use it like this:
int i=0;
foreach(DateTime dt in RandomDay())
{
Console.WriteLine(dt);
if (++i == 10)
break;
}
Start with a fixed date object (Jan 1, 1995), and add a random number of days with AddDays (obviusly, pay attention not surpassing the current date).
Random rnd = new Random();
DateTime datetoday = DateTime.Now;
int rndYear = rnd.Next(1995, datetoday.Year);
int rndMonth = rnd.Next(1, 12);
int rndDay = rnd.Next(1, 31);
DateTime generateDate = new DateTime(rndYear, rndMonth, rndDay);
Console.WriteLine(generateDate);
//this maybe is not the best method but is fast and easy to understand
One more solution to the problem, this time a class to which you provide a range you want the dates in. Its down to random minutes in the results.
/// <summary>
/// A random date/time class that provides random dates within a given range
/// </summary>
public class RandomDateTime
{
private readonly Random rng = new Random();
private readonly int totalMinutes;
private readonly DateTime startDateTime;
/// <summary>
/// Initializes a new instance of the <see cref="RandomDateTime"/> class.
/// </summary>
/// <param name="startDate">The start date.</param>
/// <param name="endDate">The end date.</param>
public RandomDateTime(DateTime startDate, DateTime endDate)
{
this.startDateTime = startDate;
TimeSpan timeSpan = endDate - startDate;
this.totalMinutes = (int)timeSpan.TotalMinutes;
}
/// <summary>
/// Gets the next random datetime object within the range of startDate and endDate provided in the ctor
/// </summary>
/// <returns>A DateTime.</returns>
public DateTime NextDateTime
{
get
{
TimeSpan newSpan = new TimeSpan(0, rng.Next(0, this.totalMinutes), 0);
return this.startDateTime + newSpan;
}
}
}
Use it like this to spit out 5 random dates between january 1st 2020 and december 31 2022:
RandomDateTime rdt = new RandomDateTime(DateTime.Parse("01/01/2020"), DateTime.Parse("31/12/2022"));
for (int i = 0; i < 5; i++)
Debug.WriteLine(rdt.NextDateTime);
I am a bit late in to the game, but here is one solution which works fine:
void Main()
{
var dateResult = GetRandomDates(new DateTime(1995, 1, 1), DateTime.UtcNow, 100);
foreach (var r in dateResult)
Console.WriteLine(r);
}
public static IList<DateTime> GetRandomDates(DateTime startDate, DateTime maxDate, int range)
{
var randomResult = GetRandomNumbers(range).ToArray();
var calculationValue = maxDate.Subtract(startDate).TotalMinutes / int.MaxValue;
var dateResults = randomResult.Select(s => startDate.AddMinutes(s * calculationValue)).ToList();
return dateResults;
}
public static IEnumerable<int> GetRandomNumbers(int size)
{
var data = new byte[4];
using (var rng = new System.Security.Cryptography.RNGCryptoServiceProvider(data))
{
for (int i = 0; i < size; i++)
{
rng.GetBytes(data);
var value = BitConverter.ToInt32(data, 0);
yield return value < 0 ? value * -1 : value;
}
}
}
Small method that returns a random date as string, based on some simple input parameters. Built based on variations from the above answers:
public string RandomDate(int startYear = 1960, string outputDateFormat = "yyyy-MM-dd")
{
DateTime start = new DateTime(startYear, 1, 1);
Random gen = new Random(Guid.NewGuid().GetHashCode());
int range = (DateTime.Today - start).Days;
return start.AddDays(gen.Next(range)).ToString(outputDateFormat);
}
Useful extension based of #Jeremy Thompson's solution
public static class RandomExtensions
{
public static DateTime Next(this Random random, DateTime start, DateTime? end = null)
{
end ??= new DateTime();
int range = (end.Value - start).Days;
return start.AddDays(random.Next(range));
}
}
Related
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Random_Files
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
var randomDateTimes = GenerateRandomDates(10000);
}
private void Form1_Load(object sender, EventArgs e)
{
}
public IEnumerable<DateTime> GenerateRandomDates(int numberOfDates)
{
var rnd = new Random(Guid.NewGuid().GetHashCode());
for (int i = 0; i < numberOfDates; i++)
{
var year = rnd.Next(1, 10000);
var month = rnd.Next(1, 13);
var days = rnd.Next(1, DateTime.DaysInMonth(year, month) + 1);
yield return new DateTime(year, month, days,
rnd.Next(0, 24), rnd.Next(0, 60), rnd.Next(0, 60), rnd.Next(0, 1000));
}
}
}
}
this generate 10,000 random datetime list.
but i want each datetime to be in this format : ToString("yyyyMMddHHmm")
and i want that some datetime will be duplicated i mean the same for example 10,000 and in this 10,000 some of them will be the same.
for example : 31/10/2099 05:51:36 to be twice or more times in the random list.
more to be random once but some of them to be the same. those are the same also to be random.
for example index 31 and index 77 the same or index 0 and index 791 the same.
because later when i make out of this files names i want to compare the files names so i need some names to be the same.
Note that DateTime doesn't have its own format; DateTime is just a struct. I suggest generating random DateTime within minDate (included) and maxDate (excluded):
private static DateTime RandomDateTime(DateTime minDate,
DateTime maxDate,
Random random = default) {
if (minDate >= maxDate)
throw new ArgumentOutOfRangeException(nameof(maxDate));
random ??= Random.Shared;
return minDate.AddTicks((long) (random.NextDouble() *
(maxDate.Ticks - minDate.Ticks)));
}
and then generate random dates, turn them into strings using required format:
Random random = new Random(123);
string report = string.Join(Environment.NewLine, Enumerable
.Range(1, 10)
.Select(_ => RandomDateTime(new DateTime(2022, 1, 1),
new DateTime(2023, 1, 1),
random))
.Select(date => $"{date:yyyyMMddHHmm}"));
Console.Write(report);
Output (fiddle):
202212260843
202211280827
202209290927
202210240558
202209271542
202201181514
202201070455
202202241223
202203130136
202208182335
I like Dmitry's answer, but the only change I'd make would be to make a DateTime generator like this:
IEnumerable<DateTime> GenerateRandomDateTimes(DateTime minimum, DateTime maximum, Random random = default)
{
if (minimum >= maximum)
throw new ArgumentOutOfRangeException(nameof(maximum));
random ??= Random.Shared;
while (true)
{
yield return minimum.AddTicks(random.NextInt64(maximum.Ticks - minimum.Ticks));
}
}
I then start with these paramters:
int requiredTotalCount = 10;
int requiredDuplicates = 2;
DateTime minimum = new DateTime(2022, 1, 1);
DateTime maximum = new DateTime(2023, 1, 1);
It's easy to generate the dates:
DateTime[] results =
GenerateRandomDateTimes(minimum, maximum)
.Take(requiredTotalCount - requiredDuplicates)
.ToArray();
results =
results
.Concat(results.Take(requiredDuplicates))
.ToArray();
Then, finally, I might want the order of the results randomized:
results = results.OrderBy(_ => Random.Shared.Next()).ToArray();
I am simulating an Iot Device (Noise Sensor) in Azure IoT hub the code below works perfectly fine.
However I want to simulate something closer to reality, where I can use different decibel ranges between different hours.
Something like this:
if 00.00- 7.00AM - Randum number between (10-20)
if 7am-9AM - Random number between (20-40)
if 11.30-1.30pm Random number between 60-80
I dont want to create a lof of IFs,Elses, as I would like to have cleaner code.
How should I do this in a structured manner?
My code below: (only the relevant method)
private static async Task SendDeviceToCloudMessagesAsync(CancellationToken ct)
{
// Initial telemetry values
int minNoise = 20;
int maxNoise = 90;
var rand = new Random();
while (!ct.IsCancellationRequested)
{
double noiseDecibels = rand.Next(minNoise, maxNoise);
// Create JSON message
string messageBody = JsonSerializer.Serialize(
new
{
eui= "58A0CB0000101DB6",
DecibelValue = noiseDecibels
});
using var message = new Message(Encoding.ASCII.GetBytes(messageBody))
{
ContentType = "application/json",
ContentEncoding = "utf-8",
};
// Add a custom application property to the message.
// An IoT hub can filter on these properties without
// access to the message body.
message.Properties.Add("noiseAlert", (noiseDecibels > 70) ? "true" : "false");
// Send the telemetry message
await s_deviceClient.SendEventAsync(message);
Console.WriteLine($"{DateTime.Now} > Sending message: {messageBody}");
await Task.Delay(60000);
}
}
I'm approaching this question in a data structure pattern (like you asked) so i would create a RangeHourDictionary class inheriting from Dictionary.
The Add method will add the ranges where the key will represent the start time and end time. The values will be an array of int of the size of 2 where the first value will represent the start range and the second value will be the end of the range.
Another function will be GetRandomRange which will get the current time and will return the value (which again, will represent the start and end of the random range)
public class RangeDictionary : Dictionary<Range, int[]>
{
public void Add(TimeSpan from, TimeSpan to, int[] randomValues)
{
Add(new Range(from, to), randomValues);
}
public int[] GetRandomRange(TimeSpan now)
{
try
{
return this.First(x => x.Key.From < now && x.Key.To > now).Value;
}
catch
{
return null;
}
}
}
public struct Range
{
public Range(TimeSpan from, TimeSpan to) : this()
{
From = from;
To = to;
}
public TimeSpan From { get; }
public TimeSpan To { get; }
}
//initialize
var lookup = new RangeDictionary();
lookup.Add(new TimeSpan(07, 0, 0), new TimeSpan(09, 0, 0), new int[2] { 10, 20 });
lookup.Add(new TimeSpan(09, 30, 0), new TimeSpan(11, 0, 0), new int[2] { 40, 50 });
lookup.Add(new TimeSpan(11, 0, 0), new TimeSpan(13, 0, 0), new int[2] { 60, 80 });
// call GetRandomRange
var res = lookup.GetRandomRange(DateTime.Now.TimeOfDay);
if (res != null){
Random random = new Random();
var randomValue = random.Next(res[0], res[1]);
}
If you have such specific conditions, the only way is to manually check, which of them applies.
private Random randomGenerator = new Random();
function decibel(DateTime d) {
int randMin = 0, randMax = 0; //the interval for the random value
var t = d.TimeOfDay;
if (t.TotalHours < 7) //0:00 - 6:59:59
{
randMin = 10; randMax = 20;
}
else if (d.TotalHours < 9) //7:00 - 8:59:59
{
randMin = 20; randMax = 40;
}
else if (d.TotalHours >= 11.5 && d.TotalHours < 13.5) //11:30 - 13:29:59
{
randMin = 60; randMax = 80;
}
...
// returns a rand with: randMin <= rand < randMax
return randomGenerator.Next(randMin, randMax);
}
I want to get the first day and last day of the month where a given date lies in. The date comes from a value in a UI field.
If I'm using a time picker I could say
var maxDay = dtpAttendance.MaxDate.Day;
But I'm trying to get it from a DateTime object. So if I have this...
DateTime dt = DateTime.today;
How to get first day and last day of the month from dt?
DateTime structure stores only one value, not range of values. MinValue and MaxValue are static fields, which hold range of possible values for instances of DateTime structure. These fields are static and do not relate to particular instance of DateTime. They relate to DateTime type itself.
Suggested reading: static (C# Reference)
UPDATE: Getting month range:
DateTime date = ...
var firstDayOfMonth = new DateTime(date.Year, date.Month, 1);
var lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddDays(-1);
UPDATE: From comments (#KarlGjertsen & #SergeyBerezovskiy)
DateTime date = ...
var firstDayOfMonth = new DateTime(date.Year, date.Month, 1);
var lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddSeconds(-1);
//OR
var lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddTicks(-1);
This is more a long comment on #Sergey and #Steffen's answers. Having written similar code myself in the past I decided to check what was most performant while remembering that clarity is important too.
Result
Here is an example test run result for 10 million iterations:
2257 ms for FirstDayOfMonth_AddMethod()
2406 ms for FirstDayOfMonth_NewMethod()
6342 ms for LastDayOfMonth_AddMethod()
4037 ms for LastDayOfMonth_AddMethodWithDaysInMonth()
4160 ms for LastDayOfMonth_NewMethod()
4212 ms for LastDayOfMonth_NewMethodWithReuseOfExtMethod()
2491 ms for LastDayOfMonth_SpecialCase()
Code
I used LINQPad 4 (in C# Program mode) to run the tests with compiler optimization turned on. Here is the tested code factored as Extension methods for clarity and convenience:
public static class DateTimeDayOfMonthExtensions
{
public static DateTime FirstDayOfMonth_AddMethod(this DateTime value)
{
return value.Date.AddDays(1 - value.Day);
}
public static DateTime FirstDayOfMonth_NewMethod(this DateTime value)
{
return new DateTime(value.Year, value.Month, 1);
}
public static DateTime LastDayOfMonth_AddMethod(this DateTime value)
{
return value.FirstDayOfMonth_AddMethod().AddMonths(1).AddDays(-1);
}
public static DateTime LastDayOfMonth_AddMethodWithDaysInMonth(this DateTime value)
{
return value.Date.AddDays(DateTime.DaysInMonth(value.Year, value.Month) - value.Day);
}
public static DateTime LastDayOfMonth_SpecialCase(this DateTime value)
{
return value.AddDays(DateTime.DaysInMonth(value.Year, value.Month) - 1);
}
public static int DaysInMonth(this DateTime value)
{
return DateTime.DaysInMonth(value.Year, value.Month);
}
public static DateTime LastDayOfMonth_NewMethod(this DateTime value)
{
return new DateTime(value.Year, value.Month, DateTime.DaysInMonth(value.Year, value.Month));
}
public static DateTime LastDayOfMonth_NewMethodWithReuseOfExtMethod(this DateTime value)
{
return new DateTime(value.Year, value.Month, value.DaysInMonth());
}
}
void Main()
{
Random rnd = new Random();
DateTime[] sampleData = new DateTime[10000000];
for(int i = 0; i < sampleData.Length; i++) {
sampleData[i] = new DateTime(1970, 1, 1).AddDays(rnd.Next(0, 365 * 50));
}
GC.Collect();
System.Diagnostics.Stopwatch sw = System.Diagnostics.Stopwatch.StartNew();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].FirstDayOfMonth_AddMethod();
}
string.Format("{0} ms for FirstDayOfMonth_AddMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].FirstDayOfMonth_NewMethod();
}
string.Format("{0} ms for FirstDayOfMonth_NewMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_AddMethod();
}
string.Format("{0} ms for LastDayOfMonth_AddMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_AddMethodWithDaysInMonth();
}
string.Format("{0} ms for LastDayOfMonth_AddMethodWithDaysInMonth()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_NewMethod();
}
string.Format("{0} ms for LastDayOfMonth_NewMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_NewMethodWithReuseOfExtMethod();
}
string.Format("{0} ms for LastDayOfMonth_NewMethodWithReuseOfExtMethod()", sw.ElapsedMilliseconds).Dump();
for(int i = 0; i < sampleData.Length; i++) {
sampleData[i] = sampleData[i].FirstDayOfMonth_AddMethod();
}
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_SpecialCase();
}
string.Format("{0} ms for LastDayOfMonth_SpecialCase()", sw.ElapsedMilliseconds).Dump();
}
Analysis
I was surprised by some of these results.
Although there is not much in it the FirstDayOfMonth_AddMethod was slightly faster than FirstDayOfMonth_NewMethod in most runs of the test. However, I think the latter has a slightly clearer intent and so I have a preference for that.
LastDayOfMonth_AddMethod was a clear loser against LastDayOfMonth_AddMethodWithDaysInMonth, LastDayOfMonth_NewMethod and LastDayOfMonth_NewMethodWithReuseOfExtMethod. Between the fastest three there is nothing much in it and so it comes down to your personal preference. I choose the clarity of LastDayOfMonth_NewMethodWithReuseOfExtMethod with its reuse of another useful extension method. IMHO its intent is clearer and I am willing to accept the small performance cost.
LastDayOfMonth_SpecialCase assumes you are providing the first of the month in the special case where you may have already calculated that date and it uses the add method with DateTime.DaysInMonth to get the result. This is faster than the other versions, as you would expect, but unless you are in a desperate need for speed I don't see the point of having this special case in your arsenal.
Conclusion
Here is an extension method class with my choices and in general agreement with #Steffen I believe:
public static class DateTimeDayOfMonthExtensions
{
public static DateTime FirstDayOfMonth(this DateTime value)
{
return new DateTime(value.Year, value.Month, 1);
}
public static int DaysInMonth(this DateTime value)
{
return DateTime.DaysInMonth(value.Year, value.Month);
}
public static DateTime LastDayOfMonth(this DateTime value)
{
return new DateTime(value.Year, value.Month, value.DaysInMonth());
}
}
If you have got this far, thank you for time! Its been fun :¬). Please comment if you have any other suggestions for these algorithms.
Getting month range with .Net API (just another way):
DateTime date = ...
var firstDayOfMonth = new DateTime(date.Year, date.Month, 1);
var lastDayOfMonth = new DateTime(date.Year, date.Month, DateTime.DaysInMonth(date.Year, date.Month));
"Last day of month" is actually "First day of *next* month, minus 1". So here's what I use, no need for "DaysInMonth" method:
public static DateTime FirstDayOfMonth(this DateTime value)
{
return new DateTime(value.Year, value.Month, 1);
}
public static DateTime LastDayOfMonth(this DateTime value)
{
return value.FirstDayOfMonth()
.AddMonths(1)
.AddMinutes(-1);
}
NOTE:
The reason I use AddMinutes(-1), not AddDays(-1) here is because usually you need these date functions for reporting for some date-period, and when you build a report for a period, the "end date" should actually be something like Oct 31 2015 23:59:59 so your report works correctly - including all the data from last day of month.
I.e. you actually get the "last moment of the month" here. Not Last day.
OK, I'm going to shut up now.
DateTime dCalcDate = DateTime.Now;
dtpFromEffDate.Value = new DateTime(dCalcDate.Year, dCalcDate.Month, 1);
dptToEffDate.Value = new DateTime(dCalcDate.Year, dCalcDate.Month, DateTime.DaysInMonth(dCalcDate.Year, dCalcDate.Month));
Here you can add one month for the first day of current month than delete 1 day from that day.
DateTime now = DateTime.Now;
var startDate = new DateTime(now.Year, now.Month, 1);
var endDate = startDate.AddMonths(1).AddDays(-1);
If you only care about the date
var firstDay = new DateTime(date.Year, date.Month, 1, 0, 0, 0, date.Kind);
var lastDay = new DateTime(date.Year, date.Month, 1, 0, 0, 0, date.Kind).AddMonths(1).AddDays(-1);
If you want to preserve time
var firstDay = new DateTime(date.Year, date.Month, 1, date.Hour, date.Minute, date.Second, date.Kind);
var lastDay = new DateTime(date.Year, date.Month, 1, date.Hour, date.Minute, date.Second, date.Kind).AddMonths(1).AddDays(-1);
Try this one:
string strDate = DateTime.Now.ToString("MM/01/yyyy");
The accepted answer here does not take into account the Kind of the DateTime instance. For example if your original DateTime instance was a UTC Kind then by making a new DateTime instance you will be making an Unknown Kind instance which will then be treated as local time based on server settings. Therefore the more proper way to get the first and last date of the month would be this:
var now = DateTime.UtcNow;
var first = now.Date.AddDays(-(now.Date.Day - 1));
var last = first.AddMonths(1).AddTicks(-1);
This way the original Kind of the DateTime instance is preserved.
I used this in my script(works for me) but I needed a full date without the need of trimming it to only the date and no time.
public DateTime GetLastDayOfTheMonth()
{
int daysFromNow = DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month) - (int)DateTime.Now.Day;
return DateTime.Now.AddDays(daysFromNow);
}
For Persian culture
PersianCalendar pc = new PersianCalendar();
var today = pc.GetDayOfMonth(DateTime.Now);
var firstDayOfMonth = pc.GetDayOfMonth(DateTime.Now.AddDays(-(today-1)));
var lastDayOfMonth = pc.GetDayOfMonth(DateTime.Now.AddMonths(1).AddDays(-today));
Console.WriteLine("First day "+ firstDayOfMonth);
Console.WriteLine("Last day " + lastDayOfMonth);
You can do it
DateTime dt = DateTime.Now;
DateTime firstDayOfMonth = new DateTime(dt.Year, date.Month, 1);
DateTime lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddDays(-1);
Give this a try. It basically calculates the number of days that has passed on DateTime.Now, then subtracts one from that and uses the new value to find the first of the current month. From there it uses that DateTime and uses .AddMonths(-1) to get the first of the previous month.
Getting the last day of last month does basically the same thing except it adds one to number of days in the month and subtracts that value from DateTime.Now.AddDays, giving you the last day of the previous month.
int NumberofDays = DateTime.Now.Day;
int FirstDay = NumberofDays - 1;
int LastDay = NumberofDays + 1;
DateTime FirstofThisMonth = DateTime.Now.AddDays(-FirstDay);
DateTime LastDayOfLastMonth = DateTime.Now.AddDays(-LastDay);
DateTime CheckLastMonth = FirstofThisMonth.AddMonths(-1);
You can try this for get current month first day;
DateTime.Now.AddDays(-(DateTime.Now.Day-1))
and assign it a value.
Like this:
dateEndEdit.EditValue = DateTime.Now;
dateStartEdit.EditValue = DateTime.Now.AddDays(-(DateTime.Now.Day-1));
Create an instance of DateTime class
DateTime dateTime = DateTime.Now;
If you want to get the last day of the month you can do this
int lastDayOfMonth = DateTime.DaysInMonth(caducidadPuntos.Year, caducidadPuntos.Month);
If you want to get the first day of the month, you can do this
DateTime firstDayMonth = new DateTime(dateTime.Year, dateTime.Month, 1);
We had the requirement of being able to get the start and end of a given dates month, including times, inclusively. We ended up utilizing the aforementioned solutions, huge thanks to everyone here, and combined it into a util class to be able to get the start and end for a given month and year number combination up to the last millisecond. Including what we moved forward with in the event it helps someone else.
The util:
public class DateUtil
{
public static (DateTime startOfMonth, DateTime endOfMonth) GetStartAndEndOfMonth(int month, int year)
{
DateTime startOfMonth = GetStartOfMonth(month, year);
DateTime endOfMonth = GetEndOfMonth(month, year);
return (startOfMonth, endOfMonth);
}
public static DateTime GetStartOfMonth(int month, int year)
{
return new DateTime(year, month, 1).Date;
}
public static DateTime GetEndOfMonth(int month, int year)
{
return new DateTime(year, month, 1).Date.AddMonths(1).AddMilliseconds(-1);
}
}
Usage:
(DateTime startOfMonth, DateTime endOfMonth) = DateUtil.GetStartAndEndOfMonth(2, 2021); // February, 2021
easy way to do it
Begin = new DateTime(DateTime.Now.Year, DateTime.Now.Month,1).ToShortDateString();
End = new DataFim.Text = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month)).ToShortDateString();
DateTime dCalcDate = DateTime.Now;
var startDate = new DateTime(Convert.ToInt32(Year), Convert.ToInt32(Month), 1);
var endDate = new DateTime(Convert.ToInt32(Year), Convert.ToInt32(Month), DateTime.DaysInMonth((Convert.ToInt32(Year)), Convert.ToInt32(Month)));
I'm trying to write a code the generate random date and time where all values of (yyyy-mm-dd hh:mm:ss) are changed
I used this code but it change only the date and fix the time
DateTime RandomDay()
{
DateTime start = new DateTime(2013, 1, 1 , 1 , 1 ,1);
Random gen = new Random();
int range = (DateTime.Today - start).Days;
return start.AddDays(gen.Next(range));
}
I said ok if I write a code that generate a random date, and store it in a variable1, then write another code that generate random time, and store it in variable2, then pick the date only from variable1, and pick the time only from variable2, then combine variable1 and variable2 together , so I can generate random date and time
therefore, I wrote this another method to generate the time
DateTime RandomTime()
{
DateTime start = new DateTime(2013, 1, 1, 1, 1, 1);
Random gen = new Random();
int range = (DateTime.Today - start).Hours;
return start.AddHours(gen.Next(range));
}
now the problem in the RandomTime method, it generate Random hours only, doesn't change the values of the minutes and seconds,
is there any suggestion to solve the code problem? is there anyway to generate random values for all (yyyy-mm-dd hh:mm:ss) ?
Here's a method that'll randomly generate every portion of the date and time.
It uses appropriate limits so the generated date is valid (years within 1-9999, months within 1-12, a call to DateTime.DaysInMonth so we don't end up with Feb 31, etc).
public IEnumerable<DateTime> GenerateRandomDates(int numberOfDates)
{
var rnd = new Random(Guid.NewGuid().GetHashCode());
for (int i = 0; i < numberOfDates; i++)
{
var year = rnd.Next(1, 10000);
var month = rnd.Next(1, 13);
var days = rnd.Next(1, DateTime.DaysInMonth(year, month) + 1);
yield return new DateTime(year, month, days,
rnd.Next(0, 24), rnd.Next(0, 60), rnd.Next(0, 60), rnd.Next(0, 1000));
}
}
To generate 10,000 of them:
var randomDateTimes = GenerateRandomDates(10000);
Here is the one line solution. 1 line for the return part ;)
private static Random _ran = new Random();
public static DateTime RandomDateTime()
{
return
DateTime.MinValue.Add(
TimeSpan.FromTicks((long) (_ran.NextDouble()*DateTime.MaxValue.Ticks)));
}
Note 1: _ran.NextDouble() gives random value between 0 and 1. so the amount of ticks you add to minimum datetime would be between 0 and DateTime.MaxValue.Ticks. So the random date time would be between minimum and maximum date time.
Note 2: DateTime.Min.Ticks is equal to 0. so this process will never overflow even if you add maximum date time ticks.
Here is how to generate 10k random date times.
DateTime[] datetimes = new DateTime[10000];
for (int i = 0; i < datetimes.Length; i++)
{
datetimes[i] = RandomDateTime();
}
You can also use this method if you want to define ranges.
public static DateTime RandomDateTime(DateTime min, DateTime max)
{
return
DateTime.MinValue.Add(
TimeSpan.FromTicks(min.Ticks + (long) (_ran.NextDouble()*(max.Ticks - min.Ticks))));
}
I'm trying to make a calendar using wpf. By using itemsPanel and more, I have a grid with 7 columns(sunday-saturday) and 6 rows(week# of month). If i can find the starting position of the first of each month by getting the weekday and week number(of the month), how can I find the week number(0-5 of each month)? Also can't I somehow just fill in the calendar from there? I'm lost and I don't know what else to try.
public partial class SchedulePage : Page
{
MainWindow _parentForm;
public int dayofweek;
public SchedulePage(MainWindow parentForm)
{
InitializeComponent();
_parentForm = parentForm;
// DateTime date = new DateTime(year, month, day);
_parentForm.bindings = new BindingCamper();
_parentForm.bindings.schedule.Add(new Schedule { WeekNo = (int) getWeekNumber(), WeekDay = dayofweek });
DataContext = _parentForm.bindings;
// lblTest.Content = dates(2011, 10, 27);
}
public double getWeekNumber()
{
dayofweek = getWeekDay(2011, 10, 31);
double h = dayofweek / 7;
double g = Math.Floor(h);
return g;
}
public int getWeekDay(int year, int month, int day)
{
//year = 2011;
//month = 10;
//day = 27;
int[] t = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
// year -= month < 3;
return (year + year / 4 - year / 100 + year / 400 + t[month - 1] + day) % 7;
}
You must use Calendar.GetDayOfWeek and Calendar.GetWeekOfYear in preference to writing yourself.
You can guarantee that if you write any date / time handling code yourself it will contain faults and won't work in different locales.
public class Row
{
public string MonthWeek { get; set; }
public string Year { get; set; }
public string Month { get; set; }
public string Day { get; set; }
public string WeekOfYear { get; set; }
}
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
var l = new List<Row>();
DateTime startDate = DateTime.Now;
DateTime d = new DateTime(startDate.Year, startDate.Month, 1);
var cal = System.Globalization.DateTimeFormatInfo.CurrentInfo.Calendar;
var ms = cal.GetWeekOfYear(new DateTime(d.Year, d.Month, 1), System.Globalization.CalendarWeekRule.FirstDay, System.DayOfWeek.Sunday);
for (var i = 1; d.Month == startDate.Month; d = d.AddDays(1))
{
var si = new Row();
var month_week = (d.Day / 7) + 1;
si.MonthWeek = month_week.ToString();
si.Month = d.Year.ToString();
si.Year = d.Month.ToString();
si.Day = d.Day.ToString();
si.WeekOfYear = cal.GetWeekOfYear(d, System.Globalization.CalendarWeekRule.FirstDay, DayOfWeek.Sunday).ToString();
l.Add(si);
}
dataGrid1.ItemsSource = l;
}
}
together with the obligatory DataGrid in the XAML:
<DataGrid AutoGenerateColumns="true" Name="dataGrid1" />
You can use Calendar.GetWeekOfYear from Globalization to do this.
Here's the MSDN docs for it: http://msdn.microsoft.com/en-us/library/system.globalization.calendar.getweekofyear.aspx
You should pass the appropriate culture properties from CultureInfo.CurrentCulture to GetWeekOfYear so that you match the current culture properly.
Example:
int GetWeekOfYear(DateTime date)
{
return Calendar.GetWeekOfYear(
date,
CultureInfo.CurrentCulture.DateTimeFormat.CalendarWeekRule,
CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek
);
}
You could easily modify this into an extension method on DateTime:
static int GetWeekOfYear(this DateTime date)
{
return Calendar.GetWeekOfYear(
date,
CultureInfo.CurrentCulture.DateTimeFormat.CalendarWeekRule,
CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek
);
}
With #Polynomial answer, I have this error:
An object reference is required for the non-static field, method, or property...
If you instanciate GregorianCalendar before then you can call the method GetWeekOfYear !
private static int GetWeekNumber(DateTime time)
{
GregorianCalendar cal = new GregorianCalendar();
int week = cal.GetWeekOfYear(time, CalendarWeekRule.FirstFullWeek, DayOfWeek.Monday);
return week;
}