How do I compare a date from txt file and date of windows?

Question

1.00/5 (2 votes)

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Hi,
I have a txt file like this:
21/05/2020 17:05:00 ; info ; info ; info
I know how to get this part of the row "21/05/2020 17:05:00" and put it as a variable.
Now I have the problem that I don't know how to compare this date and hour that is in my txt file with the date and the hour of windows.. and if it don't mach I need to get a message.
Can someone tell how the code should be?

Thank you.

What I have tried:

This is what I did to get this part of the row "21/05/2020 17:05:00"

string[] liness = File.ReadAllLines(ofd.FileName);
if (liness.Length > 0)
{
string lastLine = liness[liness.Length - 1];
string[] columns = lastLine.Split(';');
if (columns.Length > 0)
{
string lastColumn = columns[columns.Length - 5];

Posted 21-May-20 5:13am

Member 14786879

Updated 21-May-20 6:33am

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3 solutions

Solution 2

This is the same question you posted yesterday at https://www.codeproject.com/Questions/5268648/How-do-I-read-last-column-of-a-text-file-and-compa[^]. And you already have some suggestions.

Posted 21-May-20 5:38am

Richard MacCutchan

Comments

Member 14786879 21-May-20 12:16pm

Yes I know, but now I don't know how to resolve this part of the problem

Richard MacCutchan 21-May-20 12:19pm

Why not? OriginalGriff already told you how to do it. If you have a problem with his suggestion then ask him for clarification, rather than posting the same question again.

Solution 3

C#

string lastColumn = columns[columns.Length - 5];

Why on earth are you doing that? Your date and time is the first column not the last one. You access it by

C#

string date = columns[0];

Posted 21-May-20 6:34am

Richard MacCutchan

Comments

Member 14786879 21-May-20 13:04pm

You are right, I'm sorry but I'm a new entry in this world as you can see. I'm trying to do this program as I can, but it seems it don't work.
I tried as you say and it work good, now I have to understand better how to go on

Richard MacCutchan 21-May-20 15:25pm

Well we all had to start somewhere, and learn from scratch. But you would do better to get hold of some good teaching materials to get started. Trying to learn from a forum like this will take far longer. There is a very good free book that you can download from the great Charles Petzold. Go to .NET Book Zero by Charles Petzold[^] and have a look at it.

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phil.o · Accepted Answer · 2020-05-21T05:22:00

Solution 1

You first have to get a proper DateTime value out of the string from the file:

C#

// Top of file
using System.Globalization;

string dateString = /* get your date string here */;
DateTime dateValue = DateTime.ParseExact(dateString, "dd/MM/yyyy HH:mm:ss", CultureInfo.CurrentCulture);

Then you can compare it to the current datetime. However, this gets a litlle tricky since you may want to compare only on a part of the values (for example, do not take into account the milliseconds). The implementation depends on your specification.

Posted 21-May-20 5:22am

phil.o

Updated 21-May-20 6:25am

v2

Comments

Member 14786879 21-May-20 12:18pm

When I try your solution is give me this error: "It's not possible from convert 'string' to 'System.IFormatProvider'. Do you know why?

phil.o 21-May-20 12:25pm

My bad, I corrected my answer.

Member 14786879 21-May-20 13:02pm

I tried it again like:
string[] liness = File.ReadAllLines(ofd.FileName);
if (liness.Length > 0)
{
string lastLine = liness[liness.Length - 1];
string[] columns = lastLine.Split(';');
if (columns.Length > 0)
{
string date = columns[0];

string dateString = date;
DateTime dateValue = DateTime.ParseExact(dateString, "dd/MM/yyyy HH:mm:ss", CultureInfo.CurrentCulture);

But it say that there is this error on last row: "String not recognized as a valid DateTime value."

phil.o 21-May-20 13:26pm

Withot knowing what exact value there is in the string, it is hard to tell a solution. It is time for you to start a debug session and investigate this value which cannot be parsed. Do you know how to conduct a debug session?

Member 14786879 21-May-20 13:34pm

For the exact value you mean what there is in the variable "date"? Because if you mean that in the txt file he is going to read this string "21/05/2020 17:05:00 ; others info ; other info ; other info" and I'm going to read just the first "column" that contains just this "21/05/2020 17:05:00".
No I don't know how to conduct a debug session, I'm looking on others forum on google that have my same problem, but at moment I didn't find an answer that's why I have registered here and asked for help

phil.o 21-May-20 13:40pm

What is in the file is one thing; but this is what is exacly in the date variable which matters.
Tutorial: Learn to debug C# code using Visual Studio
Put a breakpoint on the line string date = columns[0];, and start a debug session (F5). When the program will get to the breakpoint, its execution will pause, and you'll be able to execute it line by line (F11) and watch for the values held in variables.

Member 14786879 21-May-20 13:52pm

Ok, the program read on the txt file this:
"03/04/2019 11:22:09 --- \t" and he put it on the variable "date".
My txt file is like a log, so there are many rows like "21/05/2020 17:05:00 ; others info ; other info ; other info"
In this code I just need to read last row.

phil.o 21-May-20 14:10pm

You have to get rid of --- \t at the end of the string. This is what prevents the date from being properly parsed.

Member 14786879 21-May-20 14:28pm

string lastLine = liness[liness.Length - 1];
string[] columns = lastLine.Split(';');
if (columns.Length > 0)
{
string date = columns[0];

string dateString = date;
dateString = dateString.Remove(19);

DateTime dateValue = DateTime.ParseExact(dateString, "dd/MM/yyyy HH:mm:ss", CultureInfo.CurrentCulture);
if (dateValue.Date == DateTime.Now.Date)
{
MessageBox.Show("OK");
}
else
{
MessageBox.Show("BAD");
}

Ok I found how to get rid of --- \t. Now I'm trying to compare what I have in the variable dateString with the date and hour of windows, but as I'm doing it just compare the date and the hour..
How should I fix it?