C# 提取 A 点和 B 点之间的部分字符串
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Extract part of a string between point A and B
提问by TheGateKeeper
I am trying to extract something from an email. The general format of the email will always be:
我正在尝试从电子邮件中提取一些内容。电子邮件的一般格式将始终为：
blablablablabllabla hello my friend.
[what I want]
Goodbye my friend blablablabla
Now I did:
现在我做了：
string.LastIndexOf("hello my friend");
string.IndexOf("Goodbye my friend");
This will give me a point before it starts, and a point after it starts. What method can I use for this? I found:
这将在它开始之前给我一个点，在它开始之后给我一个点。我可以使用什么方法？我发现：
String.Substring(Int32, Int32)
But this only takes the start position.
但这只是开始位置。
What can I use?
我可以使用什么？
采纳答案by Eric J.
Substring takes the start index (zero-based) and the number of characters you want to copy.
子字符串采用起始索引（从零开始）和要复制的字符数。
You'll need to do some math, like this:
您需要做一些数学运算，如下所示：
string email = "Bla bla hello my friend THIS IS THE STUFF I WANTGoodbye my friend";
int startPos = email.LastIndexOf("hello my friend") + "hello my friend".Length + 1;
int length = email.IndexOf("Goodbye my friend") - startPos;
string sub = email.Substring(startPos, length);
You probably want to put the string constants in a const string.
您可能想将字符串常量放在const string.
回答by Alexander Corwin
try myStr.substring(start,end);
尝试 myStr.substring(start,end);
回答by L.B
you can also use Regex
你也可以使用正则表达式
string s = Regex.Match(yourinput,
@"hello my friend(.+)Goodbye my friend",
RegexOptions.Singleline)
.Groups[1].Value;
回答by Rune FS
You can simply calculate the length from the start and end
您可以简单地计算从开始和结束的长度
const string startText = "hello my friend";
var start = str.LastIndexOf(startText) + startText.Length;
var end = str.IndexOf("Goodbye my friend");
var length = end -start;
str.Substring(start,length);
回答by pravi.net
string s1 = "find a string between within a lengthy string";
string s2 = s1.IndexOf("between").ToString();
string output = s1.Substring(0, int.Parse(s2));
Console.WriteLine("string before between is : {0}", output);
Console.ReadKey();
