String retrieve question

[Jason Huang]

Hi,

In C#, how do I retrieve a special sub string within a big string?
e.g.,
the "...fdsajk...ABC123...fdfdskafdl... ..." string has 5000 characters,
and I want to retrieve the string "123" which is right after the "ABC",
given that counting the index of the "123" is nearly impossible.
Thanks for help.


Jason

 

[Franck]

the following code return a string of all character to the left of the
string your searching for. just check the lenght of it and thats it.

public static string LeftOf(string src, char c)
{
string ret=src;
int idx=src.IndexOf(c);
if (idx != -1)
{
ret=src.Substring(0, idx);
}
return ret;
}

*code taken from : http://www.codeproject.com/cs/library/stringhelpers.asp

 

[Jon Skeet [C# MVP]]

In C#, how do I retrieve a special sub string within a big string?
e.g.,
the "...fdsajk...ABC123...fdfdskafdl... ..." string has 5000 characters,
and I want to retrieve the string "123" which is right after the "ABC",
given that counting the index of the "123" is nearly impossible.
Thanks for help.

What do you mean by "counting the index of the 123 is nearly
impossible"? What's wrong with using IndexOf?

 

[Niels Ull]

Alternatively, use a regular expression with a lookbehind prefix.
So if you want a digit sequence that comes after ABC, search for

(?<=ABC)\d+