Error while converting string to datetime in c#

Question

I have a DateTime, i'm trying to convert it to string, then convert it back to DateTime to format it. But i keep getting "string isn't recognized as valid datetime string". Any ideas?

var data = list_2.Entries.Select(c => new clients { code = cli_code, last_backup = c.Name, last_backup_date = c.AsFile.ClientModified.ToLocalTime() }).LastOrDefault(); 
var last_backup_date = data.last_backup_date;
var last_backup_date_string = Convert.ToString(last_backup_date);
var last_backup_date_formatted = DateTime.ParseExact(last_backup_date_string, "dd/MM/yyyy HH:MM:ss", CultureInfo.InvariantCulture);
var today_date = DateTime.Today;

i can put the output from the ```data.last_backup_date ``` if you'd like — Matthew Almeida, Jun 23 '20 at 15:18
we need to see an example of how last_backup_date looks like — Daniele Sartori, Jun 23 '20 at 15:20
What is the actual datatype of `var last_backup_date = data.last_backup_date;` since you need to convert it to string with this line `Convert.ToString(last_backup_date);` ? — Rand Random, Jun 23 '20 at 15:21
Well if it is of type `DateTime` in the first place, why do you need to first convert it to a `string` just to parse it back to a `DateTime`? — Rand Random, Jun 23 '20 at 15:24
because i want to format it. It comes in the normal US standard. I want to format it to dd/mm/yyyy — Matthew Almeida, Jun 23 '20 at 15:25
Judging from your variable names are you just simply looking for `var last_backup_date_formatted = data.last_backup_date.ToString("dd/MM/yyyy HH:mm:ss");`? — Rand Random, Jun 23 '20 at 15:25

score 3 · Accepted Answer · answered Jun 23 '20 at 15:25

3

Since you already have a DateTime, you could just format it:

string s = last_backup_date.ToString("dd/MM/yyyy", System.Globalization.CultureInfo.InvariantCulture);

There is no need to first convert it to a string and then try to convert it back to a DateTime. A DateTime object itself has no specific format by the way.

answered Jun 23 '20 at 15:25

mm8

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yeah, but that leaves my datetime as a string and thus i can't order it on my datagrid – Matthew Almeida Jun 23 '20 at 15:31
What do you mean? How would convert it to and back from a string make any difference? – mm8 Jun 23 '20 at 15:32
@MatthewAlmeida - than you need to apply the format of the datetime object on your datagridcolumn in winforms eg. https://stackoverflow.com/questions/4033113/how-to-format-datetime-columns-in-datagridview – Rand Random Jun 23 '20 at 15:32
You could format it in the `DataGrid` only if that's what you want. – mm8 Jun 23 '20 at 15:32
@MatthewAlmeida - wpf https://stackoverflow.com/questions/7978249/date-formatting-in-wpf-datagrid – Rand Random Jun 23 '20 at 15:32
1

@mm8 Straight forward, beat me to it. Good answer. – Greg Jun 23 '20 at 15:47

score 0 · Answer 2 · answered Jun 23 '20 at 15:23

0

Can you try this?

Var last_backup_date_string = last_backup_date.ToString("dd/MM/yyyy HH:MM:ss", CultureInfo.InvariantCulture)

answered Jun 23 '20 at 15:23

redevilliers

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the string formatted, but the datetime continues the same – Matthew Almeida Jun 23 '20 at 15:27
@MatthewAlmeida: A `DateTime` object has no specific format... – mm8 Jun 23 '20 at 15:29

score 0 · Answer 3 · answered Jun 23 '20 at 15:34

Based on the information you have, the conversion should not be an issue. However, the problem area is probably in your ParseExact. Your current date format starts with month not the day. You should be able to do the format to display in your preferred manner.

Console.WriteLine($"{date.ToString("dd/MM/yyyy")}");
Console.WriteLine($"{date.ToString("MMMM dd, yyyy")}");
Console.WriteLine($"{date.ToString("MM-dd-yyyy")}");

Otherwise you could use the DateTime.Parse method or DateTime.TryParse so you do not have to specify the culture variation.

Example:

DateTime date;
var current = DateTime.Now.ToString();
if(DateTime.TryParse(current, out date))
     Console.WriteLine(date);

DateTime date;
var current = "6/22/2020 10:03:40 AM";
if(DateTime.TryParse(current, out date))
     Console.WriteLine($"{date:dd/MM/yyyy}");

Error while converting string to datetime in c#

3 Answers3