Develop Reference

Need to refer to second to the last element of array of partial filenames

I need to find distinct values of partial filenames in an array of filenames. I'd like to do it in one line.
So, I have something like that as a filenames:
string[] filenames = {"aaa_ab12345.txt", "bbb_ab12345.txt", "aaa_ac12345.txt", "bbb_ac12345"}
and I need to find distinct values for ab12345 part of it.
So I currently have something like that:
string[] filenames_partial_distinct = Array.ConvertAll(
filenames,
file => System.IO.Path.GetFileNameWithoutExtension(file)
.Split({"_","."}, StringSplitOptions.RemoveEmptyEntries)[1]
)
.Distinct()
.ToArray();
Now, I'm getting filenames that are of form of aaa_bbb_ab12345.txt. So, instead of referring to the second part of the filename, I need to refer to the second to the last.
So, how do I refer to an arbitrary element based on length of array in one line, if it's a result of Split method? Something along lines of:
Array.ConvertAll(filenames, file=>file.Split(separator)[this.Length-2]).Distinct().ToArray();
In other words, if a string method results in an array of strings, how do I immediately select element based on the length of array:
String.Split()[third from end, fifth from end, etc.];

If you use GetFileNameWithoutExtension there will be no extension and therefore splitting by '_' will do it. Then you can take the last part with .Last().
string[] filenames_partial_distinct = Array.ConvertAll(
filenames,
file => Path.GetFileNameWithoutExtension(file).Split('_').Last()
)
.Distinct()
.ToArray();
With the input
string[] filenames = { "aaa_ab12345.txt", "bbb_ab12345.txt",
"aaa_ac12345.txt", "bbb_ac12345", "aaa_bbb_ab12345.txt" };
You get the result
{ "ab12345", "ac12345" }
The StringSplitOptions.RemoveEmptyEntries is only required if there are filenames ending with _ (before the extension).

Seems you're looking for something like this:
string[] arr = filenames.Select(n => n.Substring(n.IndexOf("_") + 1, 7)).Distinct().ToArray();

I usually defer problems like this to regex. They are very powerful. This approach also gives you the opportunity to detect unexpected cases and handle them appropriately.
Here is a crude example, assuming I understood your requirements:
using System;
using System.Linq;
using System.Text.RegularExpressions;
public class Program
{
public static void Main()
{
string MyMatcher(string filename)
{
// this pattern may need work depending on what you need - it says
// extract that pattern between the "()" which is 2 characters and
// 4 digits, exactly; and can be found in `Groups[1]`.
Regex r = new Regex(#".*_(\w{2}\d{4}).*", RegexOptions.IgnoreCase);
Match m = r.Match(filename);
return m.Success
? m.Groups[1].ToString()
: null; // what should happen here?
}
string[] filenames =
{
"aaa_ab12345.txt",
"bbb_ab12345.txt",
"aaa_ac12345.txt",
"bbb_ac12345",
"aaa_bbb_ab12345.txt",
"ae12345.txt" // MyMatcher() return null for this - what should you do if this happens?
};
var results = filenames
.Select(MyMatcher)
.Distinct();
foreach (var result in results)
{
Console.WriteLine(result);
}
}
}
Gives:
ab1234
ac1234
This can be refined further, such as pre-compiled regex patterns, encapsulation in a class, etc.

Use everything before a specific character

So, I've been learning C# and I need to remove everything after the
":" character.
I've used a StreamReader to read the text file, but then I can't use the Split function, then I tried it by using an int function to import it, but then again I can't use the Split function?
What I want this to do is import a text file that's written like;
name:lastname
name2:lastname2
And so that it only shows name and name2.
I've been searching this for a couple of days but I can't seem to figure it out!
I don't know what I'm doing wrong and how to import the text file without using StreamReader or anything else.
Edit:
I'm trying to post something to a website that goes like;
example.com/q=(name without ":")
Edit 2:
StreamReader list = new StreamReader(#"list.txt");
string reader = list.ReadToEnd();
string[] split = reader.Split(":".ToCharArray());
Console.WriteLine(split);
gives output as;
System.String[]

You've got a few issues here. First, use File.ReadLines() instead of a StreamReader, its much simpler and easier:
IEnumerable<string> lines = File.ReadLines("path/to/file");
Next, your lines variable needs to be iterated so you can get to each line of the collection:
foreach (string line in lines)
{
//TODO: write split logic here
}
Then you have to split each line on the ':' character:
string[] split = line.Split(":");
Your split variable is an array of string (i.e string[]) which means you have to access a specific index of the array if you want to see its value. This is your second issue, if you pass split to Console.WriteLine() under the hood it just calls .ToString() on the object you have passed it, and with a string[] it won't automatically give you all the values, you have to write that yourself.
So if your line variable was: "name:Steve", the split variable would have two indexes and look like this:
//split[0] = "name"
//split[1] = "Steve"
I made a fiddle here that demonstrates.

I your file size small and your name:lastname in one line use:
var lines = File.ReadAllLines("filaPath");
foreach (var line in lines)
{
var array = line.Split(':');
if (array.Length > 0)
{
var name = array[0];
}
}
if name:lastname isn't in new line tell me how it's seprated

How can i analise millions of strings that merge into each other?

I have millions of strings, around 8GB worth of HEX; each string is 3.2kb in length.
Each of these strings contains multiple parts of data I need to extract.
This is an example of one such string:
GPGGA,104644.091,,,,,0,0,,,M,,M,,*43$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header Test.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ$GPGGA,104645.091,,,,,0,0,,,M,,M,,*42$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header Test.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ ÿÿ!ÿÿ"ÿÿ#ÿÿ$ÿÿ%ÿÿ&ÿÿ'ÿÿ(ÿÿ)ÿÿ*ÿÿ+ÿÿ,ÿÿ-ÿÿ.ÿÿ/ÿÿ0ÿÿ1ÿÿ$GPGGA,104646.091,,,,,0,0,,,M,,M,,*41$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header Test2ÿÿ3ÿÿ4ÿÿ5ÿÿ6ÿÿ7ÿÿ8ÿÿ9ÿÿ:ÿÿ;ÿÿ<ÿÿ=ÿÿ>ÿÿ?ÿÿ#ÿÿAÿÿBÿÿCÿÿDÿÿEÿÿFÿÿGÿÿHÿÿIÿÿJÿÿ$GPGGA,104647.091,,,,,0,0,,,M,,M,,*40$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header TestKÿÿLÿÿMÿÿNÿÿOÿÿPÿÿQÿÿRÿÿSÿÿTÿÿUÿÿVÿÿWÿÿXÿÿYÿÿZÿÿ[ÿÿ\ÿÿ]ÿÿ^ÿÿ_ÿÿ`ÿÿaÿÿbÿÿcÿÿ$GPGGA,104648.091,,,,,0,0,,,M,,M,,*4F$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header Testdÿÿeÿÿfÿÿgÿÿhÿÿiÿÿjÿÿkÿÿlÿÿmÿÿnÿÿoÿÿpÿÿqÿÿrÿÿsÿÿtÿÿuÿÿvÿÿwÿÿxÿÿyÿÿzÿÿ{ÿÿ|ÿÿ$GPGGA,104649.091,,,,,0,0,,,M,,M,,*4E$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header Test}ÿÿ~ÿÿ.ÿÿ€ÿÿ.ÿÿ‚ÿÿƒÿÿ„ÿÿ…ÿÿ†ÿÿ‡ÿÿˆÿÿ‰ÿÿŠÿÿ‹ÿÿŒÿÿ.ÿÿŽÿÿ.ÿÿ.ÿÿ‘ÿÿ’ÿÿ“ÿÿ”ÿÿ•ÿÿ$GPGGA,104650.091,,,,,0,0,,,M,,M,,*46$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Head
as you can see it is pretty much this repeated:
GPGGA,104644.091,,,,,0,0,,,M,,M,,*43$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header Test.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ$GPGGA,104645.091,,,,,0,0,,,M,,M,,*42$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32Header Test.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ ÿÿ!ÿÿ"ÿÿ#ÿÿ$ÿÿ%ÿÿ&ÿÿ'ÿÿ(ÿÿ)ÿÿ*ÿÿ+ÿÿ,ÿÿ-ÿÿ.ÿÿ/ÿÿ0ÿÿ1ÿÿ
I want to separate this string into two lists like this:
_GPSList
$GPGGA,104644.091,,,,,0,0,,,M,,M,,*43
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N
_WavList
32HeaderTest.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ
32HeaderTest.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ.ÿÿ ÿÿ!ÿÿ"ÿÿ#ÿÿ$ÿÿ%ÿÿ&ÿÿ'ÿÿ(ÿÿ)ÿÿ*ÿÿ+ÿÿ,ÿÿ-ÿÿ.ÿÿ/ÿÿ0ÿÿ1ÿÿ
Issue 1:
This repetition isn't containing within a single string, it overflows into the next string. so if some data crosses the end and start of two strings how to I deal with that?
Issue 2: How do I analyse the string and extract only the parts I need?

The solution I'm providing is not a complete answer but more like an idea which might help you get what you want.
Everything else which I present is an assumption on my behalf.
//Assuming your data is stored in a file "yourdatafile"
//Splitting all the text on "$" assuming this will separate GPSData
string[] splittedstring = File.ReadAllText("yourdatafile").Split('$');
//I found an extra string lingering in the sample you provided
//because I splitted on "$", so you gotta take that into account
var GPSList = new List<string>();
var WAVList = new List<string>();
foreach (var str in splittedstring)
{
//So if the string contains "Header" we would want to separate it from GPS data
if (str.Contains("Header"))
{
string temp = str.Remove(str.IndexOf("Header"));
int indexOfAsterisk = temp.LastIndexOf("*");
string stringBeforeAsterisk = str.Substring(0, indexOfAsterisk + 1);
string stringAfterAsterisk = str.Replace(stringBeforeAsterisk, "");
WAVList.Add(stringAfterAsterisk);
GPSList.Add("$" + stringBeforeAsterisk);
}
else
GPSList.Add("$" + str);
}
This provides the exact output as you need, only exception is with that extra string. Also some non-standard characters might look like black blocks.

Get only numbers from line in file

So I have this file with a number that I want to use.
This line is as follows:
TimeAcquired=1433293042
I only want to use the number part, but not the part that explains what it is.
So the output is:
1433293042
I just need the numbers.
Is there any way to do this?

Follow these steps:
read the complete line
split the line at the = character using string.Split()
extract second field of the string array
convert string to integer using int.Parse() or int.TryParse()

There is a very simple way to do this and that is to call Split() on the string and take the last part. Like so if you want to keep it as a string:
var myValue = theLineString.Split('=').Last();
If you need this as an integer:
int myValue = 0;
var numberPart = theLineString.Split('=').Last();
int.TryParse(numberPart, out myValue);

string setting=sr.ReadLine();
int start = setting.IndexOf('=');
setting = setting.Substring(start + 1, setting.Length - start);

A good approach to Extract Numbers Only anywhere they are found would be to:
var MyNumbers = "TimeAcquired=1433293042".Where(x=> char.IsDigit(x)).ToArray();
var NumberString = new String(MyNumbers);
This is good when the FORMAT of the string is not known. For instance you do not know how numbers have been separated from the letters.

you can do it using split() function as given below
string theLineString="your string";
string[] collection=theLineString.Split('=');
so your string gets divided in two parts,
i.e.
1) the part before "="
2) the part after "=".
so thus you can access the part by their index.
if you want to access numeric one then simply do this
string answer=collection[1];

try
string t = "TimeAcquired=1433293042";
t= t.replace("TimeAcquired=",String.empty);
After just parse.
int mrt= int.parse(t);

remove first element from array

PHP developer here working with c#.
I'm using a technique to remove a block of text from a large string by exploding the string into an array and then shifting the first element out of the array and turning what remains back into a string.
With PHP (an awesome & easy language) it was just
$array = explode('somestring',$string);
array_shift($array);
$newstring = implode(' ', $array);
and I'm done.
I get so mad at c# for not allowing me to create dynamic arrays and for not offering me default functions that can do the same thing as PHP regarding arrays. Instead of dynamic arrays I have to create lists and predefine key structures etc. But I'm new and I'm sure there are still equally graceful ways to do the same with c#.
Will someone show me a clean way to accomplish this goal with c#?
Rephrase of question: How can I remove the first element from an array using c# code.
Here is how far I've gotten, but RemoveAt throws a error while debugging so I don't believe it works:
//scoop-out feed header information
if (entry_start != "")
{
string[] parts = Regex.Split(this_string, #entry_start);
parts.RemoveAt(0);
this_string = String.Join(" ", parts);
}

I get so mad at c# for not allowing me to create dynamic arrays
You may take a look at the List<T> class. Its RemoveAt might be worth checking.
But for your particular scenario you could simply use LINQ and the Skip extension method (don't forget to add using System.Linq; to your file in order to bring it into scope):
if (entry_start != "")
{
string[] parts = Regex.Split(this_string, #entry_start).Skip(1).ToArray();
this_string = String.Join(" ", parts);
}

C# is not designed to be quick and dirty, nor it particularly specializes in text manipulation. Furthermore, the technique you use for removing some portion of a string from a beginning is crazy imho.
Why don't you just use String.Substring(int start, int length) coupled with String.IndexOf("your delimiter")?

Here is the corresponding C# code:
string input = "a,b,c,d,e";
string[] splitvals = input.Split(',');
string output = String.Join(",", splitvals, 1, splitvals.Length-1);
MessageBox.Show(output);

You can use LINQ for this:
if (entry_start != "")
this_string = String.Join(" ", Regex.Split(this_string, #entry_start).Skip(1).ToArray());

string split = ",";
string str = "asd1,asd2,asd3,asd4,asd5";
string[] ary = str.Split(new string[] { split }, StringSplitOptions.RemoveEmptyEntries);
string newstr = string.Join(split, ary, 1, ary.Count() - 1);
splits at ",". removes the first record. then combines back with ","

As stated above, you can use LINQ. Skip(int) will return an IEnumerable<string> that you can then cast back as array.
string[] myArray = new string[]{"this", "is", "an", "array"};
myArray = myArray.Skip(1).toArray();

You might be more comfortable with generic lists than arrays, which work more like PHP arrays.
List<T>
But if your goal is "to remove a block of text from a large string" then the easier way would be:
string Example = "somestring";
string BlockRemoved = Example.Substring(1);
// BlockRemoved = "omestring"
Edit
I misunderstood the question, thinking you were just removing the first element from the array where the array consisted of the characters that make up the string.
To split a string by a delimiter, look at the String.Split method instead. Some good examples are given here.