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When i used String.Split the subsequent array only contains the first value? [duplicate]

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split a string on newlines in .NET
(17 answers)
Closed 6 years ago.
After reading a text file, I pass the information through a method that splits the string to get the required information for each field. I have gotten to the point where i split the string based on new lines, but it is beyond me why when I display the subsequent array (or list it's converted to), it only shows the first half of the first split string.
An example of how the input string looks:
ASSIGNMENT
In-Class Test 02/07/2014
In-Class Test 21/04/2013
Find my code below (the numLines variable was to simply see if it was being split into the correct number of lines as it should)
private void assignmentfinder(string brief, string id)
{
string searchcrit = "ASSIGNMENT";
string assignment = brief.Substring(brief.IndexOf(searchcrit) + searchcrit.Length);
string[] assignmentsplit;
assignmentsplit = assignment.Split('\t');
List<string> Assign = new List<string>(assignmentsplit);
listBox2.DataSource = Assign;
int numLines = assignment.Split('\n').Length;
richTextBox1.Lines=(assignmentsplit);
}
The output I get is:
In-Class Test
02/07/2014
Whereas it should show the second string split as well. Any ideas?

The problem is in the value of "brief" variable. Make sure the value you are putting in "brief" variable, actually conains "\n" and "\t".

You could use regex like this:
private void assignmentfinder(string brief, string id)
{
Regex rgxLines = new Regex(#"^(.*?)[ \t]+([0-9]{2}\/[0-9]{2}\/[0-9]{4})", RegexOptions.Multiline);
MatchCollection mLines = rgxLines.Matches(brief);
foreach (Match match in mLines)
{
richTextBox1.Text += String.Format("Test: {0}{1}Date: {2}{1}{1}",
match.Groups[1].Value,
Environment.NewLine,
match.Groups[2].Value);
}
}

Your mistake is that you split for each tab (\t). Split for the new line as you say:
private void assignmentfinder(string brief, string id)
{
string searchcrit = "ASSIGNMENT";
string assignment = brief.Substring(brief.IndexOf(searchcrit) + searchcrit.Length);
string[] assignmentSplit = assignment.Split('\n'); // splitting at new line
richTextBox1.Lines = assignmentSplit;
listBox2.DataSource = assignmentSplit.ToList();
}
I hope this helps.
EDIT: Just fixed a huge mistake
Question: Is it on purpose that the string id is never used?

You could use Linq to split on new line, then on tab, skipping the first line then aggregate into a list of string:
string brief = #"ASSIGNMENT
In-Class Test 02/07/2014
In-Class Test 21/04/2013";
List<string> theLines = new List<string>();
var lines = brief.Split('\n').Skip(1).Select (b => b.Split('\t'));
foreach (var line in lines)
{
for (int i = 0; i < line.Length; i++)
{
theLines.Add(line[i]);
}
}

Writing List<String> contents to text file after deleting string

I'm trying to get the contents of a Text File, delete a line of string, and re-write back to the Text File, deleting the line of string. I'm using StreamReader to get the text, importing into a List, removing the string, then rewriting using StreamWriter. My problems arises somewhere around the removing or writing of the string. Instead of writing back the existing, non deleted contents to the text file, all the text is replaced with :
System.Collections.Generic.List`1[System.String]
My code for this function is as follows:
{
for (int i = deleteDevice.Count - 1; i >= 0; i--)
{
string split = "";
//deleteDevice[i].Split(',').ToString();
List<string> parts = split.Split(',').ToList();
if (parts.Contains(deviceList.SelectedItem.ToString()))
{
deleteDevice.Remove(i.ToString());
}
}
if (deleteDevice.Count != 0) //Error Handling
{
writer.WriteLine(deleteDevice);
}
}
deviceList.Items.Remove(deviceList.SelectedItem);
}
I would just like the script to write back any string that isn't deleted (If there is any), without replacing it. Any help is appreciated, Cheers

You can read all the info from the text file into a list and then remove from the list and rewrite that to the text file.
I would change the list 'deleteDevice' to store a string array instead and use the code below to determine which item to remove.
List<int> toRemove = new List<int>();
int i = 0;
/*build a list of indexes to remove*/
foreach (string[] x in deleteDevice)
{
if (x[0].Contains(deviceList.SelectedItem.ToString()))
{
toRemove.Add(i);
}
i++;
}
/*Remove items from list*/
foreach (int fd in toRemove)
deleteDevice.RemoveAt(fd);
/*write to text file*/
using (StreamWriter writer = new StreamWriter("Devices.txt"))
{
if (deleteDevice.Count != 0) //Error Handling
{
foreach (string[] s in deleteDevice)
{
StringBuilder sb = new StringBuilder();
for (int fds = 0; fds < s.Length; fds++ )
{
sb.Append(s[fds] + ",");
}
string line = sb.ToString();
writer.WriteLine(line.Substring(0, line.Length - 1));
}
}
}
This isn't the best solution but should work for your needs. There's probably a much easier way of doing this.

The problem is in the following line:
writer.WriteLine(deleteDevice);
You're writing deleteDevice (I assume this is of type List). List.ToString() returns the type name of the list, because this has no specific implementation. What you want is
foreach(String s in deleteDevice)
{
writer.WriteLine(s);
}

Problems
deleteDevice is of type List<string>, and because it also doesn't overload ToString(), the default behaviour of List<string>.ToString() is to return the name of the type.
Hence your line writer.WriteLine(deleteDevice); writes the string System.Collections.Generic.List1[System.String]`.
Other than that, there are many things wrong with your code...
For example, you do this:
string split = "";
and then on the line afterwards you do this:
List<string> parts = split.Split(',').ToList();
But because split is "", this will always return an empty list.
Solution
To simplify the code, you could first write a helper method that will remove from a file all the lines that match a specified predicate:
public void RemoveUnwantedLines(string filename, Predicate<string> unwanted)
{
var lines = File.ReadAllLines(filename);
File.WriteAllLines(filename, lines.Where(line => !unwanted(line)));
}
Then you can write the predicate something like this (this might not be quite right; I don't really know exactly what your code is doing because it's not compilable and omits some of the types):
string filename = "My Filename";
string deviceToRemove= deviceList.SelectedItem.ToString();
Predicate<string> unwanted = line =>
line.Split(new [] {','})
.Contains(deviceToRemove);
RemoveUnwantedLines(filename, unwanted);

Unable to Split the string accordingly

I know this question would have been asked infinite number of times, but I'm kinda stuck.
I have a string something like
"Doc1;Doc2;Doc3;12"
it can be something like
"Doc1;Doc2;Doc3;Doc4;Doc5;56"
Its like few pieces of strings separated by semicolon, followed by a number or id.
I need to extract the number/id and the strings separately.
To be exact, I can have 2 strings: one having "Doc1;Doc2;Doc3" or "Doc1;Doc2;Doc3;Doc4" and the other having just the number/id as "12" or "34" or "45" etc.
And yeah I am using C# 3.5
I understand its a pretty easy and witty question, but this guy is stuck.
Assistance required from experts.
Regards
Anurag

string.LastIndexOf and string.Substring are the keys to what you're trying to do.
var str = "Doc1;Doc2;Doc3;12";
var ind = str.LastIndexOf(';');
var str1 = str.Substring(0, ind);
var str2 = str.Substring(ind+1);

One way:
string[] tokens = str.Split(';');
var docs = tokens.Where(s => s.StartsWith("Doc", StringComparison.OrdinalIgnoreCase));
var numbers = tokens.Where(s => s.All(Char.IsDigit));

String docs = s.Substring(0, s.LastIndexOf(';'));
String number = s.Substring(s.LastIndexOf(';') + 1);

One possible approach would be this:
var ids = new List<string>();
var nums = new List<string>();
foreach (var s in input.Split(';'))
{
int val;
if (!int.TryParse(s, out val)) { ids.Add(s); }
else { nums.Add(s); }
}
where input is something like Doc1;Doc2;Doc3;Doc4;Doc5;56. Now, ids will house all of the Doc1 like values and nums will house all of the 56 like values.

you can use StringTokenizer functionality.
http://www.c-sharpcorner.com/UploadFile/pseabury/JavaLikeStringTokenizer11232005015829AM/JavaLikeStringTokenizer.aspx
split string using ";"
StringTokenizer st = new StringTokenizer(src1,";");
collect final String. that will be your ID.

You may try one of two options: (assuming your input string is in string str;
Approach 1
Get LastIndexOf(';')
Split the string based on the index. This will give you string and int part.
Split the string part and process it
Process the int part
Approach 2
Split the string on ;
Run a for loop - for (int i = 0; i < str.length - 2; i++) - this is the string part
Process str[length - 1] separately - this is the int part
Please take this as a starting point as there could be other approaches to implement a solution for this

string actual = "Doc1;Doc2;Doc3;12";
int lstindex = actual.LastIndexOf(';');
string strvalue = actual.Substring(0, lstindex);
string id = actual.Substring(lstindex + 1);

C# preg_replace?

What is the PHP preg_replace in C#?
I have an array of string that I would like to replace by an other array of string. Here is an example in PHP. How can I do something like that in C# without using .Replace("old","new").
$patterns[0] = '/=C0/';
$patterns[1] = '/=E9/';
$patterns[2] = '/=C9/';
$replacements[0] = 'à';
$replacements[1] = 'é';
$replacements[2] = 'é';
return preg_replace($patterns, $replacements, $text);

Real men use regular expressions, but here is an extension method that adds it to String if you wanted it:
public static class ExtensionMethods
{
public static String PregReplace(this String input, string[] pattern, string[] replacements)
{
if (replacements.Length != pattern.Length)
throw new ArgumentException("Replacement and Pattern Arrays must be balanced");
for (var i = 0; i < pattern.Length; i++)
{
input = Regex.Replace(input, pattern[i], replacements[i]);
}
return input;
}
}
You use it like this:
class Program
{
static void Main(string[] args)
{
String[] pattern = new String[4];
String[] replacement = new String[4];
pattern[0] = "Quick";
pattern[1] = "Fox";
pattern[2] = "Jumped";
pattern[3] = "Lazy";
replacement[0] = "Slow";
replacement[1] = "Turtle";
replacement[2] = "Crawled";
replacement[3] = "Dead";
String DemoText = "The Quick Brown Fox Jumped Over the Lazy Dog";
Console.WriteLine(DemoText.PregReplace(pattern, replacement));
}
}

You can use .Select() (in .NET 3.5 and C# 3) to ease applying functions to members of a collection.
stringsList.Select( s => replacementsList.Select( r => s.Replace(s,r) ) );
You don't need regexp support, you just want an easy way to iterate over the arrays.

public static class StringManipulation
{
public static string PregReplace(string input, string[] pattern, string[] replacements)
{
if (replacements.Length != pattern.Length)
throw new ArgumentException("Replacement and Pattern Arrays must be balanced");
for (int i = 0; i < pattern.Length; i++)
{
input = Regex.Replace(input, pattern[i], replacements[i]);
}
return input;
}
}
Here is what I will use. Some code of Jonathan Holland but not in C#3.5 but in C#2.0 :)
Thx all.

You are looking for System.Text.RegularExpressions;
using System.Text.RegularExpressions;
Regex r = new Regex("=C0");
string output = r.Replace(text);
To get PHP's array behaviour the way you have you need multiple instances of `Regex
However, in your example, you'd be much better served by .Replace(old, new), it's much faster than compiling state machines.

Edit: Uhg I just realized this question was for 2.0, but I'll leave it in case you do have access to 3.5.
Just another take on the Linq thing. Now I used List<Char> instead of Char[] but that's just to make it look a little cleaner. There is no IndexOf method on arrays but there is one on List. Why did I need this? Well from what I am guessing, there is no direct correlation between the replacement list and the list of ones to be replaced. Just the index.
So with that in mind, you can do this with Char[] just fine. But when you see the IndexOf method, you have to add in a .ToList() before it.
Like this: someArray.ToList().IndexOf
String text;
List<Char> patternsToReplace;
List<Char> patternsToUse;
patternsToReplace = new List<Char>();
patternsToReplace.Add('a');
patternsToReplace.Add('c');
patternsToUse = new List<Char>();
patternsToUse.Add('X');
patternsToUse.Add('Z');
text = "This is a thing to replace stuff with";
var allAsAndCs = text.ToCharArray()
.Select
(
currentItem => patternsToReplace.Contains(currentItem)
? patternsToUse[patternsToReplace.IndexOf(currentItem)]
: currentItem
)
.ToArray();
text = new String(allAsAndCs);
This just converts the text to a character array, selects through each one. If the current character is not in the replacement list, just send back the character as is. If it is in the replacement list, return the character in the same index of the replacement characters list. Last thing is to create a string from the character array.
using System;
using System.Collections.Generic;
using System.Linq;

asp.net Convert CSV string to string[]

Is there an easy way to convert a string from csv format into a string[] or list?
I can guarantee that there are no commas in the data.

String.Split is just not going to cut it, but a Regex.Split may - Try this one:
using System.Text.RegularExpressions;
string[] line;
line = Regex.Split( input, ",(?=(?:[^\"]*\"[^\"]*\")*(?![^\"]*\"))");
Where 'input' is the csv line. This will handle quoted delimiters, and should give you back an array of strings representing each field in the line.

If you want robust CSV handling, check out FileHelpers

string[] splitString = origString.Split(',');
(Following comment not added by original answerer)
Please keep in mind that this answer addresses the SPECIFIC case where there are guaranteed to be NO commas in the data.

Try:
Regex rex = new Regex(",(?=([^\"]*\"[^\"]*\")*(?![^\"]*\"))");
string[] values = rex.Split( csvLine );
Source: http://weblogs.asp.net/prieck/archive/2004/01/16/59457.aspx

You can take a look at using the Microsoft.VisualBasic assembly with the
Microsoft.VisualBasic.FileIO.TextFieldParser
It handles CSV (or any delimiter) with quotes. I've found it quite handy recently.

There isn't a simple way to do this well, if you want to account for quoted elements with embedded commas, especially if they are mixed with non-quoted fields.
You will also probably want to convert the lines to a dictionary, keyed by the column name.
My code to do this is several hundred lines long.
I think there are some examples on the web, open source projects, etc.

Try this;
static IEnumerable<string> CsvParse(string input)
{
// null strings return a one-element enumeration containing null.
if (input == null)
{
yield return null;
yield break;
}
// we will 'eat' bits of the string until it's gone.
String remaining = input;
while (remaining.Length > 0)
{
if (remaining.StartsWith("\"")) // deal with quotes
{
remaining = remaining.Substring(1); // pass over the initial quote.
// find the end quote.
int endQuotePosition = remaining.IndexOf("\"");
switch (endQuotePosition)
{
case -1:
// unclosed quote.
throw new ArgumentOutOfRangeException("Unclosed quote");
case 0:
// the empty quote
yield return "";
remaining = remaining.Substring(2);
break;
default:
string quote = remaining.Substring(0, endQuotePosition).Trim();
remaining = remaining.Substring(endQuotePosition + 1);
yield return quote;
break;
}
}
else // deal with commas
{
int nextComma = remaining.IndexOf(",");
switch (nextComma)
{
case -1:
// no more commas -- read to end
yield return remaining.Trim();
yield break;
case 0:
// the empty cell
yield return "";
remaining = remaining.Substring(1);
break;
default:
// get everything until next comma
string cell = remaining.Substring(0, nextComma).Trim();
remaining = remaining.Substring(nextComma + 1);
yield return cell;
break;
}
}
}
}

CsvString.split(',');

Get a string[] of all the lines:
string[] lines = System.IO.File.ReadAllLines("yourfile.csv");
Then loop through and split those lines (this error prone because it doesn't check for commas in quote-delimited fields):
foreach (string line in lines)
{
string[] items = line.Split({','}};
}

string s = "1,2,3,4,5";
string myStrings[] = s.Split({','}};
Note that Split() takes an array of characters to split on.

Some CSV files have double quotes around the values along with a comma. Therefore sometimes you can split on this string literal: ","

A Csv file with Quoted fields, is not a Csv file. Far more things (Excel) output without quotes rather than with quotes when you select "Csv" in a save as.
If you want one you can use, free, or commit to, here's mine that also does IDataReader/Record. It also uses DataTable to define/convert/enforce columns and DbNull.
http://github.com/claco/csvdatareader/
It doesn't do quotes.. yet. I just tossed it together a few days ago to scratch an itch.
Forgotten Semicolon: Nice link. Thanks.
cfeduke: Thanks for the tip to Microsoft.VisualBasic.FileIO.TextFieldParser. Going into CsvDataReader tonight.

http://github.com/claco/csvdatareader/ updated using TextFieldParser suggested by cfeduke.
Just a few props away from exposing separators/trimspaces/type ig you just need code to steal.

I was already splitting on tabs so this did the trick for me:
public static string CsvToTabDelimited(string line) {
var ret = new StringBuilder(line.Length);
bool inQuotes = false;
for (int idx = 0; idx < line.Length; idx++) {
if (line[idx] == '"') {
inQuotes = !inQuotes;
} else {
if (line[idx] == ',') {
ret.Append(inQuotes ? ',' : '\t');
} else {
ret.Append(line[idx]);
}
}
}
return ret.ToString();
}

string test = "one,two,three";
string[] okNow = test.Split(',');

separationChar[] = {';'}; // or '\t' ',' etc.
var strArray = strCSV.Split(separationChar);

string[] splitStrings = myCsv.Split(",".ToCharArray());