I have a simple question about DateTime in c#.
I have a textbox where I ask the user to input a date.
I want to validate that the textbox is not empty before parsing the string to a datetime to validate if the date is in the right format.
Here is a bit of my code:
String strStartDate = txtStartDate.txt;
DateTime StartDate = DateTime.Parse(strStartDate);
I have other text boxes for the names and such and I also validate if they are empty with a if statement like this (same if statement to validate if strStartDate is empty):
if (strFirstName.Trim() == "")
{
txtFirstName.BackColor = System.Drawing.Color.Yellow;
errorMessage = errorMessage + "First Name may not be empty. ";
}
else
{
txtFirstName.BackColor = System.Drawing.Color.White;
}
The debugger stops as soon as I try the submit button, it says that String was not recognized as a valid DateTime.
Is there a way to see if the string is empty before validating the DateTime?
You can also use TryParse:
string SomeDate = "1/1/2012";
DateTime dt;
var success = DateTime.TryParse(SomeDate, out dt);
Then you can check success to see if it was a valid date or not. This will protect you from any invalid date string, not just an empty or null string.
String.IsNullOrEmpty will do what you want
Related
I try to validate an input and then i can get input like that i want to.
Example:
if (string != validate(string))
then not valid
else
then valid
Inputs and expected output
2017-03-17T09:44:18.000+07:00 == valid
2017-03-17 09:44:18 == not valid
To check valid DateTime, you need correct DateTime format (i.e "yyyy-MM-ddTHH:mm:ss.fffzzz") and use DateTime.TryParseExact() to validate your datetime string,
Try below code to validate your datetime string,
public void ValidateDateTimeString(string datetime)
{
DateTime result = new DateTime(); //If Parsing succeed, it will store date in result variable.
if(DateTime.TryParseExact(datetime, "yyyy-MM-ddTHH:mm:ss.fffzzz", CultureInfo.InvariantCulture, DateTimeStyles.None, out result))
Console.WriteLine("Valid date String");
else
Console.WriteLine("Invalid date string");
}
Try it online
You should be able to use DateTime.TryParseExact. This will return true/false based on whether it parses correctly. You can specify the pattern to match using format parameter.
You could use regex to match the date format you want (take a look at this example as to what your Regex should look like, depending on the format you need).
function Validate(string Input)
{
System.Text.RegularExpressions.Regex MyRegex = new
System.Text.RegularExpressions.Regex("([12]\d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01]))");
return MyRegex.Match(Input).Success // returns true or false
}
Hi I am looking for a way to verify that the string that I am adding to a SqlCommand as parameter is correct.
Here is my code :
string wrongType = "This is not a date";
command.Parameters.Add("#Date", SqlDbType.DateTime).Value = wrongType;
Is there a way to check if wrongType can be converted to a SqlDbType.DateTime ?
You can use DateTime.TryParse:
string wrongType = "This is not a date";
DateTime rightTyped;
if(DateTime.TryParse(wrongType, out rightTyped))
{
command.Parameters.Add("#Date", SqlDbType.DateTime).Value = rightTyped;
}
If you get user input, you must validate input in place.
Try this:
string wrongType = "This is not a date";
DateTime date;
if(DateTime.TryParse(wrongType, out date))
{
// staff when string converted
}
The problem is the first line:
string wrongType = "This is not a date";
If it has to be a date, and if your TSQL is working against a date, then... use a date:
DateTime rightType = ...
Now it is never wrong. Basically, stop relying on strings. The rest of the code remains similar:
command.Parameters.Add("#Date", SqlDbType.DateTime).Value = rightType;
Note that you can use DateTime.Parse and DateTime.TryParse to get from string input to a DateTime.
I have passing a date in query string as the format of 02-2014.and using this date I done the search.It is working and the result is perfect .but when I change the query string value in the browser then the error will showing.In this condition I need only some message,So how can we check the query string date value is in correct format.my code is
string dateToSearch = HttpContext.Current.Request["date"];
if (!string.IsNullOrEmpty(dateToSearch))
{
dateToSearch = dateToSearch.Trim();
string year = null;
string month = null;
var dates = dateToSearch.Split("-".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
if (dates.Length > 0)
{
month = dates[0];
year = dates[1];
}
}
Just use DateTime.TryParseExact with the format string MM-yyyy. This will tell you whether your input string is in the format you specified and if so, it returns the parsed DateTime object via an out parameter.
Try this:
DateTime date;
if (DateTime.TryParseExact(text, "MM'-'yyyy",
CultureInfo.InvariantCulture,
DateTimeStyles.None,
out date))
{
// Success
}
else
{
// Parse failed
}
in my application i have send one link to User's email id he can download software on clicking this link....now my url is look like....
http://www.abc.co.in/Download.aspx?period=11/04/2013%2012:29:20%20PM&ProductName=Otja
and my code for retriving this value on pageload download.aspx page is
string PName = Request.QueryString["ProductName"] as string;
string myDate = Request.QueryString["period"];
if (!String.IsNullOrEmpty(myDate))
{
myDate = myDate.Replace("!", ":");
}
DateTime dt1 = Convert.ToDateTime(myDate);
DateTime dt2 = DateTime.Now;
TimeSpan variable = dt2 - dt1;
if (variable.TotalMinutes > 5)
{
//Response.Write("Download time is expired now");
lblmsg.Visible = true;
lblmsg.Text = "Download time is expired now";
}
else
{
lblmsg.Visible = true;
lblmsg.Text = "U can Still Download";
}
but this is not working i tested and before 5 Minute and after minutes it is only shows "You can still download" so i think my error is that i can not retrive that productname and period value on querystring on this download.aspx page..please help me.. thanks
i think there should be error..... String was not recognized as a valid DateTime. thats why it is pass null value so any solution ???
You said you think that your code is not able to retrieve the query params. Why don't you confirm that by printing the values first.
The Request.QueryString() looks correct.
There could be issue with your logic which may case the else to execute.
Based on more information provided by you please try this -
Variable myDate value must be “11-04-2013 06 36”. Please confirm.
Instead of Convert.ToDateTime(myDate); try this
DateTime.ParseExact(myDate, "dd-MM-yyyy HH:mm", System.Globalization.CultureInfo.InvariantCulture);
I am trying to convert a date value of YYYY/MM/DD from a textbox to datetime, when the value is correct it is ok but when I tried to input an incorrect data to check with the database, the error return as String was not recognized as a valid DateTime.
Here is my code:
protected void btnSubmit_Click(object sender, EventArgs e)
{
string format = "YYYY-MM-DD HH:MM:SS";
DateTime birthday = DateTime.Parse(txtBday.Text);
DataSet ds = new DataSet();
ds = (newService.checkAccount());
if (ds.Tables[0].Rows.Count > 0)
{
foreach (DataRow dRow in ds.Tables[0].Rows)
{
string accountNo = dRow["ACCTNO"].ToString();
DateTime birthDate = DateTime.Parse(dRow["DATEOFBIRTH"].ToString());
if (accountNo == txtAccountNo.Text.ToString() && birthDate == birthday)
{
lblMessage.Text = "<br>Account Number Exist. You may now proceed with the registration<br><br>";
HttpCookie lmsCookie = new HttpCookie("id");
lmsCookie.Value = txtAccountNo.Text;
Response.Cookies.Add(lmsCookie);
Response.Redirect("Step2.aspx");
}
else
{
Image2.Visible = false;
lblMessage.Text = "<br>Please check your information and try again." + "<br>Be sure you are entering the correct information.For further assistance, call (+632) 404-2790.<br><br>";
}
}
}
}
For example I will enter a data that will match in the database, the program will proceed otherwise if I am going to input a data that does not match with any of the existing records in the database, the program will triggers an error, String was not recognized as valid datetime.
When you parsing can fail for a reason other than a bug, instead of this:
DateTime birthDate = DateTime.Parse(dRow["DATEOFBIRTH"].ToString())
(which throws an exception as you've seen), use DateTime.TryParse:
DateTime birthDate;
if (DateTime.TryParse(dRow["DATEOFBIRTH"].ToString(), out birthDate))
{
// Success case
}
else
{
// Handle error case
}
I note that you're not using your format variable, by the way. If you know what the format will be (and your question disagrees with your code, btw) it would be better to use TryParseExact:
if (DateTime.TryParseExact(dRow["DATEOFBIRTH"].ToString(), "YYYY/MM/dd",
CultureInfo.InvariantCulture, DateTimeStyles.None,
out birthDate))
...
Definitely, it will throw an exception when an unsupported format is tried to convert into a datetime. So, before converting you should Parse it by using DateTime.TryParse method.
Sovel ,
Step 1:
this._checkInOutDTO.NgayCham = DateTime.Parse(this.DGVDuLieuVaoRa.Rows[num15].Cells[1].Value.ToString());
// this._checkInOutDTO.NgayCham = Convert.ToDateTime(this.DGVDuLieuVaoRa.Rows[num15].Cells[1].Value.ToString());
Step 2:
Format : dd/MM/yyyy