如何将字符串的长度限制为 150 个字符？

Question

I tried the following:

var a = description.Substring(0, 150);

However this gives a problem if the length of description is less than 150 chars. So is there another way I can limit the length to 150 that won't give an error when string length is for example 20.

Answer 1

var a = description == null 
        ? string.Empty 
        : description.Substring(0, Math.Min(150, description.Length));

Answer 2

var a = description.Substring(0, Math.Min(150, description.Length));

只需抓取150个字符的子字符串，或整个字符串，以较短者为准。

Answer 3

Try the following extension method

public static string LimitTo(this string data, int length) {
  return (data == null || data.Length < length) 
    ? data 
    : data.Substring(0, length);
}

Answer 4

The String Length Attribute works for C#:

[StringLength(150)]
public string MyProperty { get; set; }

Answer 5

I think you actually want this.

public static string LimitTo(this string data, int length) {
  return (data == null || data.Length <= length)   // Less than or equal to
    ? data 
    : data.Substring(0, length);
}

Answer 6

It will be good if your environment support you to use below method. (As @christian-cody suggested.)

[StringLength(150)]
public string MyProperty { get; set; }

You have to include the below namespace to use it.

using System.ComponentModel.DataAnnotations;

Answer 7

everyone seems to be overcomplicating this, all you need is simply

var a = description;
if (description.length > 150) a = description.Substring(0, 150);

sometimes you just need to think around the problem.

Answer 8

Strings are immutable, even if you could create an instance that worked the way you wanted, as soon as you assign another value to your variable, it would be a different instance of type string .

If you want a string property that has a max of 150 characters, then write a property where you check the value in the setter and throw an exception if it's more than 150 characters.

If you want a string parameter to a method that has a max of 150 characters, then at the top of the method, check to see if it is more than 150 characters, if it is, throw an exception.

Answer 9

var a = description.Substring(0, description.Length > 150 ? 150 : description.Length);

Answer 10

As of C# 8.0 we can utilize the Range operator and end up with this:

var x = description[..150];