String.Format is not working as expected C#

Question

I'm trying to format content of my file like this:

0126252019-05-06 14:47:06 1098500020

But everytime I'm getting this results:

01262524. 5. 2019. 14:47:08 1098500020

Obliviously date and time are not formated as I wanted.

Here is my code:

StreamWriter file = new System.IO.StreamWriter("C:\\MyMainFolder\\MyFilesFolder\\" + 15050 + ".flr");
file.WriteLine(12625.ToString("D6") + string.Format("{0:yyyy-MM-dd HH:mm:ss}", DateTime.Now + " " + 1098500020));
file.Close();

I've tried to format DateTime.Now as I wrote

string.Format("{0:yyyy-MM-dd HH:mm:ss}"

But looks like its not working

Thanks guys

Cheers!

Answer 1

The problem is that + is applied as string concatenation in the expression below:

string.Format("{0:yyyy-MM-dd HH:mm:ss}", DateTime.Now + " " + 1098500020);
//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
//                         C# makes this one string, and passes it for formatting.

Moving the concatenation that you plan to do inside the format string will fix the problem:

string.Format("{0:yyyy-MM-dd HH:mm:ss} 1098500020", DateTime.Now);

Answer 2

You are passing DateTime.Now + " " + 1098500020 to string.Format which isn't going to be parsed by that format string you have specified. To fix that you should move the ) .

However, you should create the entire string, including the prefix , with string.Format , or for clearer code use string interpolation , for example:

var someInteger = 12625;
var line = $"{someInteger:D6}{DateTime.Now:yyyy-MM-dd HH:mm:ss} 1098500020";

Answer 3

consider using

string.Format("{0:yyyy-MM-dd HH:mm:ss}", DateTime.Now)  + " " + 1098500020

Pass the date only to string format