ParseExact没有解析字符串的日期，日期与序数但没有年份

Question

I have reviewed the answer to Parse very long date format to DateTime in C# and it goes a little way to fixing my problem, but I fear I might be stumbling into an unrelated issue, and thus have opened this new thread.

Dates come into my process as a string that I have no control over. They always represent a date in the future. An example would be " Wednesday 26th November at 18:30 ". Notice, the day has an ordinal, and that there is no year.

I need to get these into a DateTime structure, so that I can... well, do DateTime things to them!

I am currently using the following snippet (adjusted from the afore mentioned question), but it's still failing on the last conditional, which I would expect it to pass.

public DateTime ParseOrdinalDateTime(string dt)
{
    DateTime d;
    if (DateTime.TryParseExact(dt, "dddd d\"st\" MMMM \"at\" hh:mm", null, DateTimeStyles.AssumeLocal, out d))
        return d;
    if (DateTime.TryParseExact(dt, "dddd d\"nd\" MMMM \"at\" hh:mm", null, DateTimeStyles.AssumeLocal, out d))
        return d;
    if (DateTime.TryParseExact(dt, "dddd d\"rd\" MMMM \"at\" hh:mm", null, DateTimeStyles.AssumeLocal, out d))
        return d;
    if (DateTime.TryParseExact(dt, "dddd d\"th\" MMMM \"at\" hh:mm", null, DateTimeStyles.AssumeLocal, out d))
        return d;

    throw new InvalidOperationException("Not a valid DateTime string");
}

Answer 1

如果您正在接收24小时格式化时间，那么您应该将字符串解析为"dddd d\\"th\\" MMMM \\"at\\" HH:mm" （注意大写的Hs）。

Answer 2

1) Swap the hh:mm to HH:mm (using 24 hours..)
2) Set culture to en-US

Such as

 string dateString = "Wednesday 26th November at 18:30"; string format = "dddd d\\"th\\" MMMM \\"at\\" HH:mm"; DateTime dt; DateTime.TryParseExact(dateString, format, new CultureInfo("en-US"), DateTimeStyles.AssumeLocal, out dt); 

edit - formatted

Answer 3

Your format string is a little bit off and you need to set a culture:

private static void Main(string[] args)
{
    DateTime result = ParseOrdinalDateTime("Friday 29th August at 18:30");
}

public static DateTime ParseOrdinalDateTime(string dt)
{
    DateTime d;

    if (DateTime.TryParseExact(dt, "dddd d\"th\" MMMM \"at\" HH:mm",  CultureInfo.CreateSpecificCulture("en-GB"), DateTimeStyles.AssumeLocal, out d))
    {
        return d;
    }

    throw new InvalidOperationException("Not a valid DateTime string");
}