从字符串末尾对字符串进行子串

Question

我需要从字符串的末尾删除两个字符.

所以:

string = "Hello Marco !"

一定是

Hello Marco

我该怎么做？

Answer 1

你可以做:

string str = "Hello Marco !";
str = str.Substring(0, str.Length - 2);

Answer 2

s = s.Substring(0, Math.Max(0, s.Length - 2))

包括长度小于2的情况

Answer 3

C# 8 引入了允许您编写的索引和范围

str[^2..]

这相当于

str.Substring(str.Length - 2, str.Length)

事实上，这几乎就是编译器将生成的内容，因此没有开销。

请注意，ArgumentOutOfRangeException如果范围不在字符串内，您将得到一个。

Answer 4

关于什么

string s = "Hello Marco !";
s = s.Substring(0, s.Length - 2);

Answer 5

I will trim the end for unwanted characters:

s = s.TrimEnd(' ', '!');

To ensure it works even with more spaces. Or better if you want to ensure it works always, since the input text seems to come from the user:

Regex r = new Regex(@"(?'purged'(\w|\s)+\w)");
Match m = r.Match("Hello Marco   !!");
if (m.Success)
{
    string result = m.Groups["purged"].Value;
}

With this you are safer. A purge based on the fact the last two characters has to be removed is too weak.