Question

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C# int ToString format on 2 char int?

Sorry for the simplicity, but this one is eluding me. Pretty much I have a list of 36 records, and if the id is less than 10, I need it to return 01, 02, 03… 09, instead of 1, 2, 3… 9.

Here is the code I have so far and I would have thought this would work. This is C# .NET:

for (int i = 1; i <= 36; i++)
{
    if (i.ToString().Length == 1)
    {
        i.ToString().PadLeft(2,'0');
    }

    Response.Write("Test: " + i);
}

Any help would be appreciated, thanks in advance!

Answer 1

Your problem is i is still an integer, it needs to be assigned to a string

  for (int i = 1; i <= 36; i++)
    {
        var iString = i.ToString();

        if(iString.Length == 1)
        {
            iString = iString.PadLeft(2,'0'); //RIGHT HERE!!!
        }
        Response.Write("Test: " + iString);
    }

However, much of this code is superflous, the if statement is not needed. Pad will only ped with zeroes up to the length (2) given. If it’s already 2 or more characters long, it won’t pad anything. All you need is this

    for (int i = 1; i <= 36; i++)
    {
        var iString = i.ToString().PadLeft(2,'0');
        Response.Write("Test: " + iString);
    }

For that matter, the variable is no longer needed.

    for (int i = 1; i <= 36; i++)
    {
        Response.Write("Test: " + i.ToString().PadLeft(2,'0'));
    }

And if you’ll be padding with zeroes all the time, and not some other character, you could just do this

    for (int i = 1; i <= 36; i++)
    {
        Response.Write("Test: " + i.ToString("00"));
    }

And you should get into the habit of using string.Format

    for (int i = 1; i <= 36; i++)
    {
        Response.Write(string.Format("Test: {0}", i.ToString("00")));
    }

And to simplify the string.Format even further:

    for (int i = 1; i <= 36; i++)
    {
        Response.Write(string.Format("Test: {0:00}", i));
    }