2个字符串之间的正则表达式值

Question

How do I get the value in between 2 strings? I have a string with format d1048_m325 and I need to get the value between d and _. How is this done in C#?

Thanks,

Mike

Answer 1

(?<=d)\d+(?=_)

should work (assuming that you're looking for an integer value between d and _ ):

(?<=d) # Assert that the previous character is a d
\d+    # Match one or more digits
(?=_)  # Assert that the following character is a _

In C#:

resultString = Regex.Match(subjectString, @"(?<=d)\d+(?=_)").Value;

Answer 2

Alternatively if you want more freedom as to what can be between the d and _:

d([^_]+)

which is

d       # Match d
([^_]+) # Match  (and capture) one or more characters that isn't a _

Answer 3

Even though the regex answers found on this page are probably good, I took the C# approach to show you an alternative. Note that I typed out every step so it's easy to read and to understand.

//your string
string theString = "d1048_m325";

//chars to find to cut the middle string
char firstChar = 'd';
char secondChar = '_';

//find the positions of both chars
//firstPositionOfFirstChar +1 to not include the char itself
int firstPositionOfFirstChar = theString.IndexOf(firstChar) +1; 
int firstPositionOfSecondChar = theString.IndexOf(secondChar);

//the middle string will have a length of firstPositionOfSecondChar - firstPositionOfFirstChar  
int middleStringLength = firstPositionOfSecondChar - firstPositionOfFirstChar;

//cut!
string middle = theString.Substring(firstPositionOfFirstChar, middleStringLength);

Answer 4

You can also use lazy quantifier

d(\\d+?)_