why does DateTime.ToString("dd/MM/yyyy") give me dd-MM-yyyy?

Question

Slash is a date delimiter, so that will use the current culture date delimiter.

If you want to hard-code it to always use slash, you can do something like this:

DateTime.ToString("dd'/'MM'/'yyyy")

Pass CultureInfo.InvariantCulture as the second parameter of DateTime, it will return the string as what you want, even a very special format:

DateTime.Now.ToString("dd|MM|yyyy", CultureInfo.InvariantCulture)

will return: 28|02|2014

Add CultureInfo.InvariantCulture as an argument:

using System.Globalization;

...

var dateTime = new DateTime(2016,8,16);
dateTime.ToString("dd/MM/yyyy", CultureInfo.InvariantCulture);

Will return:

"16/08/2016"

If you use MVC, tables, it works like this:

<td>@(((DateTime)detalle.fec).ToString("dd'/'MM'/'yyyy"))</td>