为什么TimeSpan.ParseExact无法正常工作 [英] Why does TimeSpan.ParseExact not work

问题描述

这是一个有点怪异。解析文本字段具有有效时间跨度失败，如果我尝试是precise！

This is a bit wierd. Parsing a text field with a valid timespan fails if I try to be precise!

const string tmp = "17:23:24";
//works
var t1 = TimeSpan.Parse(tmp);
//fails
var t2 = TimeSpan.ParseExact(tmp, "hh:mm:ss", System.Globalization.CultureInfo.InvariantCulture);

第二解析失败与异常输入字符串的不正确的格式。从日期时间。

The second parse fails with an exception "Input string was not in a correct format." from DateTime.

推荐答案

从文档：

在格式字符串，包括任何其他非转义字符
  空格字符，是PTED为自定义格式说明符间$ P $。在
  大多数情况下，任何其他非转义字符的presence导致
  FormatException。

Any other unescaped character in a format string, including a white-space character, is interpreted as a custom format specifier. In most cases, the presence of any other unescaped character results in a FormatException.

有两种方法可以包括在格式字符串文字字符：

There are two ways to include a literal character in a format string:

  

• 在单引号（文字字符串分隔符）括起来。

• Enclose it in single quotation marks (the literal string delimiter).

$ P $用反斜杠（\\），这是PTED作为转义字符间precede它。这意味着，在C＃中，格式字符串必须
  要么是@ -quoted，或文字字符必须是由pceded $ P $
  额外的反斜杠。

Precede it with a backslash ("\"), which is interpreted as an escape character. This means that, in C#, the format string must either be @-quoted, or the literal character must be preceded by an additional backslash.

.NET框架没有定义的语法在时间分隔符
  区间。这意味着，日期和时间之间的分离器，
  小时和分钟，分钟和秒，秒的分数
  第二必须全部在格式字符串被视为字符文字。

The .NET Framework does not define a grammar for separators in time intervals. This means that the separators between days and hours, hours and minutes, minutes and seconds, and seconds and fractions of a second must all be treated as character literals in a format string.

所以，解决的办法是指定格式字符串为

So, the solution is to specify the format string as

TimeSpan.ParseExact(tmp, "hh\\:mm\\:ss", CultureInfo.InvariantCulture)

这篇关于为什么TimeSpan.ParseExact无法正常工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！