C# 如何将字符串限制为不超过特定长度？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/17249593/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How can I limit a string to no more than a certain length?
提问by
I tried the following:
我尝试了以下方法：
var Title = LongTitle.Substring(0,20)
This works but not if LongTitle has a length of less than 20. How can I limit strings to a maximum of 20 characters but not get an error if they are just for example 5 characters long?
这有效，但如果 LongTitle 的长度小于 20，则无效。如何将字符串限制为最多 20 个字符，但如果它们只是例如 5 个字符长，则不会出错？
回答by Zbigniew
Make sure that length won't exceed LongTitle(nullchecking skipped):
确保长度不会超过LongTitle（null跳过检查）：
int maxLength = Math.Min(LongTitle.Length, 20);
string title = LongTitle.Substring(0, maxLength);
This can be turned into extension method:
这可以变成扩展方法：
public static class StringExtensions
{
/// <summary>
/// Truncates string so that it is no longer than the specified number of characters.
/// </summary>
/// <param name="str">String to truncate.</param>
/// <param name="length">Maximum string length.</param>
/// <returns>Original string or a truncated one if the original was too long.</returns>
public static string Truncate(this string str, int length)
{
if(length < 0)
{
throw new ArgumentOutOfRangeException(nameof(length), "Length must be >= 0");
}
if (str == null)
{
return null;
}
int maxLength = Math.Min(str.Length, length);
return str.Substring(0, maxLength);
}
}
Which can be used as:
可以用作：
string title = LongTitle.Truncate(20);
回答by cuongle
string title = new string(LongTitle.Take(20).ToArray());
回答by Peter Rasmussen
If the string Length is bigger than 20, use 20, else use the Length.
如果字符串长度大于 20，则使用 20，否则使用长度。
string title = LongTitle.Substring(0,
(LongTitle.Length > 20 ? 20 : LongTitle.Length));
回答by AgentFire
Shortest, the:
最短的是：
var title = longTitle.Substring(0, Math.Min(20, longTitle.Length))
回答by Sebastian
You can use the StringLength attribute. That way no string can be stored that is longer (or shorter) than a specified length.
您可以使用 StringLength 属性。这样就不能存储比指定长度长（或短）的字符串。
请参阅：http: //msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.stringlengthattribute%28v=vs.100%29.aspx
[StringLength(20, ErrorMessage = "Your Message")]
public string LongTitle;
