如何将字符串限制为不超过一定长度?
我尝试了以下方法:
var Title = LongTitle.Substring(0,20)
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,但如果它们仅为5个字符长则不会出错?
确保长度不超过LongTitle
(跳过null
检查):
int maxLength = Math.Min(LongTitle.Length, 20); string title = LongTitle.Substring(0, maxLength);
这可以转换为扩展方法:
public static class StringExtensions { /// /// Truncates string so that it is no longer than the specified number of characters. /// /// String to truncate. /// Maximum string length. /// Original string or a truncated one if the original was too long. 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); } }
哪个可以用作:
string title = LongTitle.Truncate(20);
最短的,:
var title = longTitle.Substring(0, Math.Min(20, longTitle.Length))
string title = new string(LongTitle.Take(20).ToArray());
如果字符串Length大于20,请使用20,否则使用Length。
string title = LongTitle.Substring(0, (LongTitle.Length > 20 ? 20 : LongTitle.Length));
您可以使用StringLength属性。 这样就不能存储比指定长度更长(或更短)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;