Question

I have many strings like “20120117” and “20120321”. I need to convert it in a new string with this format: “2012/01/17” and “2012/03/21”. So, there is a way to do this?

I try:

string dateString = string.format("{0:d", "20120321");

and

string dateString = string.format("{0:yyyy/MM/dd", "20120321"); 

and

string dateString = int.Parse("20120321").ToString("yyyy/MM/dd");

I all cases i don’t reach my goal. =/

So, i can i do this?

OBS: There is a way to do that without parse to datetime?

Answer 1

You have to parse those values in DateTime objects first.

Example :

DateTime dt = DateTime.ParseExact("20120321", "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture);
var result = dt.ToString("yyyy/MM/dd");

---

Edit after your comments on other answers:
if you don’t like parsing because it may throw excepations, you can always use TryParse, like this:

DateTime dt;
bool success = DateTime.TryParseExact("20120321", "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None, out dt);
if (success)
{
    var result = dt.ToString("yyyy/MM/dd");
}

---

Edit 2: Using TryParseExact with multiple formats:

DateTime dt;
string[] formats = { "yyyyMMdd", "yyyy" };

bool success = DateTime.TryParseExact("20120321", formats, System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None, out dt);
if (success)
{
    var result = dt.ToString("yyyy/MM/dd");
    Console.WriteLine(result);
}

It will produce 2012/03/21 when using “20120321” as input value, and 2012/01/01 when using 2012 as input value.