Question

This has been asked a few different ways but I am debating on “my way” vs “your way” with another developer. Language is C#.

I want to parse a pipe delimited string where the first 2 characters of each chunk is my tag.

The rules. Not my rules but rules I have been given and must follow.
I can’t change the format of the string.
This function will be called possibly many times so efficiency is key.
I need to keep is simple.
The input string and tag I am looking for may/will change during runtime.

Example input string: AOVALUE1|ABVALUE2|ACVALUE3|ADVALUE4
Example tag I may need value for: AB

I split string into an array based on delimiter and loop through the array each time the function is called. I then looked at the first 2 characters and return the value minus the first 2 characters.

The “other guys” way is to take the string and use a combination of IndexOf and SubString to find the starting point and ending point of the field I am looking for. Then using SubString again to pullout the value minus the first 2 characters. So he would say IndexOf(“|AB”) the find then next pipe in the string. This would be the start and end. Then SubString that out.

Now I should think that IndexOf and SubString would parse the string each time at a char by char level so this would be less efficient than using large chunks and reading the string minus the first 2 characters. Or is there another way the is better then what both of us has proposed?

Answer 1

Something like this may work ok

string myString = "AOVALUE1|ABVALUE2|ACVALUE3|ADVALUE4";
string selector = "AB";

var results = myString.Split('|').Where(x => x.StartsWith(selector)).Select(x => x.Replace(selector, ""));

Returns: list of the matches, in this case just one “VALUE2”

If you are just looking for the first or only match this will work.

 string result = myString.Split('|').Where(x => x.StartsWith(selector)).Select(x => x.Replace(selector, "")).FirstOrDefault();