Develop Reference

How to extract single string from file line

I know this is probably a newbie question but I need help with my first C# program.
I need to extract some strings from a file. Every line looks like this:
630 FWTRGS782BT a-p 66.12.111.198
and need to only retrieve (it is a serial number):
FWTRGS782BT
I was thinking the correct way could to use line.Substring() but I really don't know how to retrieve it.
Actually every serial number starts by FG or FW, so it could may be possible to extract whenever I get a match with those first two letters and get up till the end of the string (or /t)?

Try this:
string line = "630 FWTRGS782BT a-p 66.12.111.198";
var lineArr = line.Split(new char[] {' '}, StringSplitOptions.RemoveEmptyEntries);
var requiredText = lineArr.Where(x => !string.IsNullOrEmpty(x) && x.StartsWith("FW") || x.StartsWith("FG"));

Here an example of how to read all serial numbers from a file
private List<string> GetAllSerialNumbersFromDocument(string pathToFile) //something like "C://folder/folder/file.txt"
{
List<string> serialNumbers = new List<string>(); //list where all serial numbers are stored
using (System.IO.StreamReader file = new StreamReader(pathToFile)) //Use 'using' because TextReader implements IDisposable
{
string line;
while ((line = file.ReadLine()) != null) //read all lines
{
serialNumbers.Add(GetSerialNumber(line)); //Get serial number of line and save it into list
}
}
return serialNumbers; //return all serial numbers
}
private string GetSerialNumber(string line)
{
var singleElements = line.Split(new char[] {' '}, StringSplitOptions.RemoveEmptyEntries); //split elements
return singleElements.First(x => x.StartsWith("FW") || x.StartsWith("FG")); //Get serial number
}

var input = "630 FWTRGS782BT a-p 66.12.111.198";
var output = input.Split( new char []{ ' ' },
StringSplitOptions.RemoveEmptyEntries);
Console.WriteLine(output[1]); //➙ FWTRGS782BT

Replace List<string> with words from a file, keep the order

public static List<string> items = new List<string>() { "a","b","c","d","e" };
I am trying to change each of those from loading a file and replacing with their current inventory.
if (File.Exists("darColItems.txt") == true)
{
char c = ',';
StreamReader st = new StreamReader("darColItems.txt");
temp = st.ReadToEnd().ToCharArray();
foreach (c in temp)
{
}
st.Close();
}
Edit: Taking a file such as: iron,bronze,gold,diamond,iron and taking each name and place it into the list for each spot.
File.txt: "string1","string2","string3","string4","string5"
Startup of program:
List inventory (current):
"a","b","c","d","e"
Load inventory....
List inventory (final):
"string1","string2","string3","string4","string5"

Assuming that you actually want to replace all items in the list with all items in the file in the order of occurence and the delimiter is comma. You could use String.Split:
items = File.ReadAllText("path").Split(new [] { ',' }, StringSplitOptions.None).ToList();
If you have quotes around the words in the file which you want to remove, you can use String.Trim:
items = File.ReadAllText("path")
.Split(new char[] { ',' }, StringSplitOptions.None)
.Select(s => s.Trim('"', ' ')) // remove quotes + spaces at the beginning and end
.ToList();

//keep filename in a constant/variable for easy reuse (better, put it in a config file)
const string SourceFile = "darColItems.txt";
//what character separates data elements (if the elements may contain this character you may instead want to look into a regex; for now we'll keep it simple though, & assume that's not the case
const char delimeter = ',';
//here's where we'll store our values
var values = new List<string>();
//check that our input file exists
if (File.Exists(SourceFile))
{
//using statement ensures file is closed & disposed, even if there's an error mid-process
using (var reader = File.OpenText(SourceFile))
{
string line;
//read each line until the end of file (at which point the line read will be null)
while ((line = reader.ReadLine()) != null)
{
//split the string by the delimiter (',') and feed those values into our list
foreach (string value in line.Split(delimiter)
{
values.Add(value);
}
}
}
}

Read text file and split it over

So, I know my headline is a bit confusing, I will explain.
My code looks like this:
string filename = "C:\\C#\\maplist.txt"; // please put the text file path.
string filename2 = "C:\\C#\\zemaplist.txt";
string map;
StreamReader sr = new StreamReader(filename);
StreamWriter sw = new StreamWriter(filename2);
List<string> maps = new List<string> { };
while ((map = sr.ReadLine()) != null)
{
maps.Add(map);
}
sr.Close();
for (int i = 0; i < maps.Count; i++)
{
Console.WriteLine(maps[i]);
sw.WriteLine(maps[i]);
}
sw.Close();
and what i need to do is when the code read a new line, in my line there is
"Hey,Hey"
I want to split the , from each other so I can take both of them as other parameters, so that the first Hey will be added to maps and the other hey will be maps2,
How can I do that?

You can use Split() function to Split the given String based on delimiter.
Try This:
while ((map = sr.ReadLine()) != null)
{
maps.Add(map.Split(',')[0].Trim());
maps2.Add(map.Split(',')[1].Trim());
}
Simple Code:
using System.IO;
string filename = "C:\\C#\\maplist.txt"; // please put the text file path.
string filename2 = "C:\\C#\\zemaplist.txt";
string map;
StreamWriter sw = new StreamWriter(filename2);
List<string> maps = new List<string> { };
List<string> maps2 = new List<string> { };
String [] allLines = File.ReadAllLines(filename);
foreach(String line in allLines)
{
maps.Add(line.Split(',')[0].Trim());
maps2.Add(line.Split(',')[1].Trim());
}
for (int i = 0; i < maps.Count; i++)
{
Console.WriteLine(maps[i]);
sw.WriteLine(maps[i]);
}
sw.Close();
Solution 2:
String mapItem1="";
String mapItem2="";
if(maps.Count == maps2.Count)
{
for(int i=0;i<maps.Count;i++)
{
mapItem1=maps[i];
mapItem2=maps2[i];
}
}

while ((map = sr.ReadLine()) != null)
{
string[] split = map.Split(',');
//First Hey would be split[0], second Hey would be split[1]
maps.Add(split[0].Trim());
maps2.Add(split[1].Trim());
}
The Split method should help you out with that.
If you want to trim leading whitespace characters, you can use the .Trim() method on a string.

Use Split().
string heys = "Hey,Hey";
string[] splitArray = heys.Split(',');
Then you have:
splitArray[0] = "Hey";
splitArray[1] = "Hey";

Why even bother reading line by line? Read the entire file, replace the new line chars for a "," (to prevent last and first elements from different lines to be treated as one), and loop through a clean string.
string fileContent = Regex.Replace(File.ReadAllText("test.txt"), #"\r", ",");
List<string> mapList = new List<string>();
foreach (string map in Regex.Split(fileContent.Replace(#"\s+", ""), ","))
{
mapList.Add(map.Trim());
}

Extract data from text file

I need to extract some data from a text file and insert to columns in excel sheet. I know how to do this if the rows and the length of the string is known.
try
{
using (System.IO.StreamReader sr = new System.IO.StreamReader("test.txt")
{
string line;
while ((line = sr.ReadLine()) != null)
{
listSNR.Items.Add(line.Substring (78,4));
}
}
}
But the particular text file is complex and the starting index or the length cannot be provided. But the starting word (PCPU01) of the row is known.
Eg: PCPU01,T2716,0.00,0.01,0.00,0.00
output:
T2716 0 0.01 0 0
In that case can somebody please let me know how to extract the texts?

using(System.IO.StreamReader sr = new System.IO.StreamReader("test.txt"))
{
string line;
while((line = sr.ReadLine()) != null)
{
string[] split = line.Split(',');
//...
}
}
split[0] will return "PCPU01", split[1] "T2716" and so on.

You can split one string into an array of strings, separated by a given character. This way, you could split the source string by a comma and use the resulting strings to build your output. Example:
string source = "PCPU01,T2716,0.00,0.01,0.00,0.00";
string[] parts = source.Split(',');
StringBuilder result = new StringBuilder();
result.Append(parts[1]); // The second element in the array, i.e. T2716
result.Append(" ");
result.Append(parts[2]); // 0.00
... // And so on...
return result.ToString() // return a string, not a StringBuilder

I hope this helps a little bit. You might have to tweak it to your needs. But this is a higher level code that gives you general idea of extracting data off a notepad.
DialogResult result = openFileDialog.ShowDialog();
Collection<Info> _infoCollection = new Collection<Info>();
Collection<string> listOfSubDomains = new Collection<string>();
string[] row;
string line;
// READ THE FILE AND STORE IT IN INFO OBJECT AND STORE TAHT INFO OBJECT IN COLLECTION
try
{
using (StreamReader reader = new StreamReader(openFileDialog.FileName))
{
while((line = reader.ReadLine()) != null)
{
Info _info = new Info();
row = line.Split(' ');
_info.FirstName = row[0];
_info.LastName = row[1];
_info.Email = row[2];
_info.Id = Convert.ToInt32(row[3]);
_infoCollection.Add(_info);
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}

thanks for the answers. What i wanted is to identify the particular line in the text file and split the line into columns. So i was able to do this by calling a GetLine method:
string line15=GetLine(#"test.txt",15);
public string GetLine(string fileName, int line)
{
using (System.IO.StreamReader ssr = new System.IO.StreamReader("test.txt"))
//using (var ssr = new StreamReader("test.txt"))
{
for (int i = 1; i < line; i++)
ssr.ReadLine();
return ssr.ReadLine();
}
}
Then i splitted this line by using the delimiter (,)

This was my approach in C#. It takes a string input (which you can get out of a text file) and an int with which line you want to get. It then separates the string at a given seperator char to a list which in turn is then read out. If the given line number is lower than the count of the created list, the entry is given back.
public string GetLine(string multiline,int line)
{
List<string> lines = new List<string>();
lines = multiline.Split('\n').ToList<string>();
return lines.Count >= line ? lines[line] : "";
}

How to remove empty lines from a formatted string

How can I remove empty lines in a string in C#?
I am generating some text files in C# (Windows Forms) and for some reason there are some empty lines. How can I remove them after the string is generated (using StringBuilder and TextWrite).
Example text file:
THIS IS A LINE
THIS IS ANOTHER LINE AFTER SOME EMPTY LINES!

If you also want to remove lines that only contain whitespace, use
resultString = Regex.Replace(subjectString, #"^\s+$[\r\n]*", string.Empty, RegexOptions.Multiline);
^\s+$ will remove everything from the first blank line to the last (in a contiguous block of empty lines), including lines that only contain tabs or spaces.
[\r\n]* will then remove the last CRLF (or just LF which is important because the .NET regex engine matches the $ between a \r and a \n, funnily enough).

Tim Pietzcker - it is not working for me. I have to change a little bit, but thanks!
Ehhh C# Regex.. I had to change it again, but this it working well:
private string RemoveEmptyLines(string lines)
{
return Regex.Replace(lines, #"^\s*$\n|\r", string.Empty, RegexOptions.Multiline).TrimEnd();
}
Example:
http://regex101.com/r/vE5mP1/2

You could try String.Replace("\n\n", "\n");

Try this
Regex.Replace(subjectString, #"^\r?\n?$", "", RegexOptions.Multiline);

private string remove_space(string st)
{
String final = "";
char[] b = new char[] { '\r', '\n' };
String[] lines = st.Split(b, StringSplitOptions.RemoveEmptyEntries);
foreach (String s in lines)
{
if (!String.IsNullOrWhiteSpace(s))
{
final += s;
final += Environment.NewLine;
}
}
return final;
}

private static string RemoveEmptyLines(string text)
{
var lines = text.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
var sb = new StringBuilder(text.Length);
foreach (var line in lines)
{
sb.AppendLine(line);
}
return sb.ToString();
}

None of the methods mentioned here helped me all the way, but I found a workaround.
Split text to lines - collection of strings (with or without empty strings, also Trim() each string).
Add these lines to multiline string.
public static IEnumerable<string> SplitToLines(this string inputText, bool removeEmptyLines = true)
{
if (inputText == null)
{
yield break;
}
using (StringReader reader = new StringReader(inputText))
{
string line;
while ((line = reader.ReadLine()) != null)
{
if (removeEmptyLines && !string.IsNullOrWhiteSpace(line))
yield return line.Trim();
else
yield return line.Trim();
}
}
}
public static string ToMultilineText(this string text)
{
var lines = text.SplitToLines();
return string.Join(Environment.NewLine, lines);
}

Based on Evgeny Sobolev's code, I wrote this extension method, which also trims the last (obsolete) line break using TrimEnd(TrimNewLineChars):
public static class StringExtensions
{
private static readonly char[] TrimNewLineChars = Environment.NewLine.ToCharArray();
public static string RemoveEmptyLines(this string str)
{
if (str == null)
{
return null;
}
var lines = str.Split(TrimNewLineChars, StringSplitOptions.RemoveEmptyEntries);
var stringBuilder = new StringBuilder(str.Length);
foreach (var line in lines)
{
stringBuilder.AppendLine(line);
}
return stringBuilder.ToString().TrimEnd(TrimNewLineChars);
}
}

I found a simple answer to this problem:
YourradTextBox.Lines = YourradTextBox.Lines.Where(p => p.Length > 0).ToArray();
Adapted from Marco Minerva [MCPD] at Delete Lines from multiline textbox if it's contain certain string - C#

I tried the previous answers, but some of them with regex do not work right.
If you use a regex to find the empty lines, you can’t use the same for deleting.
Because it will erase "break lines" of lines that are not empty.
You have to use "regex groups" for this replace.
Some others answers here without regex can have performance issues.
private string remove_empty_lines(string text) {
StringBuilder text_sb = new StringBuilder(text);
Regex rg_spaces = new Regex(#"(\r\n|\r|\n)([\s]+\r\n|[\s]+\r|[\s]+\n)");
Match m = rg_spaces.Match(text_sb.ToString());
while (m.Success) {
text_sb = text_sb.Replace(m.Groups[2].Value, "");
m = rg_spaces.Match(text_sb.ToString());
}
return text_sb.ToString().Trim();
}

This pattern works perfect to remove empty lines and lines with only spaces and/or tabs.
s = Regex.Replace(s, "^\s*(\r\n|\Z)", "", RegexOptions.Multiline)