Wer*_*ght 4 .net string datetime parsing strtotime
是否有相当于PHP的strtotime().NET Framework功能.我在谈论它处理字符串的能力如下:
显然DateTime.Parse(),Convert.ToDateTime()不要这样做.
我发现的最接近的是一个只能处理其中一些的小类:http://refactormycode.com/codes/488-parse-relative-date
编辑:我对C#编译时功能不感兴趣.问题是在运行时将人类相对日期/时间字符串转换为DateTime(即"now" - > DateTime.Now等).
到目前为止还没有答案,我根据给出的例子做了.它支持大多数情况,除了"上周六"(或一周中的其他日子).
/// <summary>
/// Parse a date/time string.
///
/// Can handle relative English-written date times like:
/// - "-1 day": Yesterday
/// - "+12 weeks": Today twelve weeks later
/// - "1 seconds": One second later from now.
/// - "5 days 1 hour ago"
/// - "1 year 2 months 3 weeks 4 days 5 hours 6 minutes 7 seconds"
/// - "today": This day at midnight.
/// - "now": Right now (date and time).
/// - "next week"
/// - "last month"
/// - "2010-12-31"
/// - "01/01/2010 1:59 PM"
/// - "23:59:58": Today at the given time.
///
/// If the relative time includes hours, minutes or seconds, it's relative to now,
/// else it's relative to today.
/// </summary>
internal class RelativeDateParser
{
private const string ValidUnits = "year|month|week|day|hour|minute|second";
/// <summary>
/// Ex: "last year"
/// </summary>
private readonly Regex _basicRelativeRegex = new Regex(@"^(last|next) +(" + ValidUnits + ")$");
/// <summary>
/// Ex: "+1 week"
/// Ex: " 1week"
/// </summary>
private readonly Regex _simpleRelativeRegex = new Regex(@"^([+-]?\d+) *(" + ValidUnits + ")s?$");
/// <summary>
/// Ex: "2 minutes"
/// Ex: "3 months 5 days 1 hour ago"
/// </summary>
private readonly Regex _completeRelativeRegex = new Regex(@"^(?: *(\d) *(" + ValidUnits + ")s?)+( +ago)?$");
public DateTime Parse(string input)
{
// Remove the case and trim spaces.
input = input.Trim().ToLower();
// Try common simple words like "yesterday".
var result = TryParseCommonDateTime(input);
if (result.HasValue)
return result.Value;
// Try common simple words like "last week".
result = TryParseLastOrNextCommonDateTime(input);
if (result.HasValue)
return result.Value;
// Try simple format like "+1 week".
result = TryParseSimpleRelativeDateTime(input);
if (result.HasValue)
return result.Value;
// Try first the full format like "1 day 2 hours 10 minutes ago".
result = TryParseCompleteRelativeDateTime(input);
if (result.HasValue)
return result.Value;
// Try parse fixed dates like "01/01/2000".
return DateTime.Parse(input);
}
private static DateTime? TryParseCommonDateTime(string input)
{
switch (input)
{
case "now":
return DateTime.Now;
case "today":
return DateTime.Today;
case "tomorrow":
return DateTime.Today.AddDays(1);
case "yesterday":
return DateTime.Today.AddDays(-1);
default:
return null;
}
}
private DateTime? TryParseLastOrNextCommonDateTime(string input)
{
var match = _basicRelativeRegex.Match(input);
if (!match.Success)
return null;
var unit = match.Groups[2].Value;
var sign = string.Compare(match.Groups[1].Value, "next", true) == 0 ? 1 : -1;
return AddOffset(unit, sign);
}
private DateTime? TryParseSimpleRelativeDateTime(string input)
{
var match = _simpleRelativeRegex.Match(input);
if (!match.Success)
return null;
var delta = Convert.ToInt32(match.Groups[1].Value);
var unit = match.Groups[2].Value;
return AddOffset(unit, delta);
}
private DateTime? TryParseCompleteRelativeDateTime(string input)
{
var match = _completeRelativeRegex.Match(input);
if (!match.Success)
return null;
var values = match.Groups[1].Captures;
var units = match.Groups[2].Captures;
var sign = match.Groups[3].Success ? -1 : 1;
Debug.Assert(values.Count == units.Count);
var dateTime = UnitIncludeTime(units) ? DateTime.Now : DateTime.Today;
for (int i = 0; i < values.Count; ++i)
{
var value = sign*Convert.ToInt32(values[i].Value);
var unit = units[i].Value;
dateTime = AddOffset(unit, value, dateTime);
}
return dateTime;
}
/// <summary>
/// Add/Remove years/days/hours... to a datetime.
/// </summary>
/// <param name="unit">Must be one of ValidUnits</param>
/// <param name="value">Value in given unit to add to the datetime</param>
/// <param name="dateTime">Relative datetime</param>
/// <returns>Relative datetime</returns>
private static DateTime AddOffset(string unit, int value, DateTime dateTime)
{
switch (unit)
{
case "year":
return dateTime.AddYears(value);
case "month":
return dateTime.AddMonths(value);
case "week":
return dateTime.AddDays(value * 7);
case "day":
return dateTime.AddDays(value);
case "hour":
return dateTime.AddHours(value);
case "minute":
return dateTime.AddMinutes(value);
case "second":
return dateTime.AddSeconds(value);
default:
throw new Exception("Internal error: Unhandled relative date/time case.");
}
}
/// <summary>
/// Add/Remove years/days/hours... relative to today or now.
/// </summary>
/// <param name="unit">Must be one of ValidUnits</param>
/// <param name="value">Value in given unit to add to the datetime</param>
/// <returns>Relative datetime</returns>
private static DateTime AddOffset(string unit, int value)
{
var now = UnitIncludesTime(unit) ? DateTime.Now : DateTime.Today;
return AddOffset(unit, value, now);
}
private static bool UnitIncludeTime(CaptureCollection units)
{
foreach (Capture unit in units)
if (UnitIncludesTime(unit.Value))
return true;
return false;
}
private static bool UnitIncludesTime(string unit)
{
switch (unit)
{
case "hour":
case "minute":
case "second":
return true;
default:
return false;
}
}
}
我确信可以改进,但它应该用英语处理大多数情况.如果您看到改进(如区域设置错误等),请发表评论.
编辑:如果相对时间包括时间,则固定为相对于现在.