How to Parse a date string from a text file on PC to DateTime

Question

---EDITED---

I have a simple C# Windows Form. "c:\date.txt" is just (DateTime.Now). Later I will create some code to update this file, but for now, I'm having a problem with debugging. It builds fine, but debug throws an exception at the date.txt file... The code is as follows:

public partial class Form1 : Form
{
    private void timer1_Tick(object sender, EventArgs e)
    {
        DateTime dt = DateTime.Parse(@"C:\date.txt"); // Exception Thrown Here
                      // Should be: (File.ReadAllText(@"C:\date.txt"))
        DateTime dn = DateTime.Now;
        TimeSpan dc = (dn - dt);
        label1.Text = ("Days = " + dc.Days + 
                    "\nHours = " + dc.Hours +
                    "\nMins = " + dc.Minutes +
                    "\nSecs = " + dc.Seconds);
    }
}

FormatException was unhandled... The string was not recognized as a valid DateTime. There is an unknown word starting at index 0. "When converting a string to DateTime, parse the string to take the date before putting each variable into the DateTime object."

I am parsing! I've tried (new StreamReader...ToString()). I've tried Convert.ToDateTime(...). I've tried making it a method... I've tried TryParse. Nothing is helping. What do I need to do here to make this thing read the string from the file?

maybe you should first read out the lines of text in the file and parse those instead of trying to parse the filepath — grabthefish, Jan 01 '15 at 20:03
Well, you need to pass a string that represents a date to `DateTime.Parse`, not a file name — Rufus L, Jan 01 '15 at 20:04
You might want to refer this as an example: http://www.dotnetperls.com/datetime-parse DateTime.Parse expects a datetime string as input and not a file name. — Rush, Jan 01 '15 at 20:05
Yup. DateTime is trying to parse a string that isn't there. --> string dateThen = File.ReadAllText(@"c:\date.txt"); <-- Now DateTime can parse a string. Duh. I'm just learning and have been pouring over MSDN and StackOverflow for days. Thanks, Guys. — Fixer, Jan 02 '15 at 20:26

score 3 · Accepted Answer · answered Jan 01 '15 at 20:06

3

If the file only contains a single line that contains a date, you can do this:

DateTime dt = DateTime.Parse(File.ReadAllText(@"C:\date.txt"));

answered Jan 01 '15 at 20:06

Rufus L

36,127
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score 1 · Answer 2 · answered Jan 01 '15 at 20:06

1

Of course, you are trying to parse the string "C:\date.txt" to a DateTime. You better try this:

System.IO.StreamReader file = new System.IO.StreamReader(@"c:\date.txt");
string txt = file.ReadLine();
DateTime dt = DateTime.Parse(txt);
file.Close();

answered Jan 01 '15 at 20:06

dario

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don't forget if your using a `StreamReader` to close and dispose of it, or wrap it inside a using statement – grabthefish Jan 01 '15 at 20:08

Fixer · Answer 3 · 2016-06-17T12:18:52.953

Thank you everyone. These were great answers. YES - DateTime.Parse is looking to parse a "string", not a file or a file.ToString()...

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        if (!File.Exists(@"C:\tmp\date.txt"))
        {
            File.WriteAllText(@"C:\tmp\date.txt", DateTime.Now.ToString());
        }
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        DateTime dn = DateTime.Now;
        DateTime dt = DateTime.Parse(File.ReadAllText(@"C:\tmp\date.txt"));
                          // Read the Text ^      From the File ^
        TimeSpan dc = dn - dt;
        label1.Text = "Now: " + dn.ToString() +
                    "\nThen: " + dt.ToString() +
                    "\nDifference..." +
                    "\nDays: " + dc.Days.ToString() +
                    "\nHours: " + dc.Hours.ToString() +
                    "\nMins: " + dc.Minutes.ToString() +
                    "\nSecs: " + dc.Seconds.ToString();
    }
}

This was part of a date/time counter that counts up from the last time an occurrence happened at work. A lot of people stop and ask questions about the display and about the issue that sparked the last reset of the counter.

How to Parse a date string from a text file on PC to DateTime

3 Answers3