Develop Reference

How To read Block of text in a text file

I have a file in which i have to read text between startscriptexpression$ and Finish scriptExpression$, and also read between startupdatedescription$ and startupdatedescription$[
The problem is that i want to re write the code in a cleaner format.
My Code:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
namespace Vesrion
{
class Program
{
static void Main(string[] args)
{
string path = #"C:\Users\Development\Desktop\Read\Test.txt";
using (var reader = new StreamReader(path))
{
var textInBetween = new List<string>();
var ListOFDescription = new List<string>();
string NewString = "";
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
//Reads First line,
switch (line)
{
case "StartScriptExpression$":
continue;
case "FinishScriptExpression$":
if (line.Contains("FinishScriptExpression$"))
{
line = "";
}
string Something = string.Join("", textInBetween);
textInBetween = line.Split(',').ToList();
string[] lines = Something.Split(
new string[] { Environment.NewLine },
StringSplitOptions.None);
foreach (var S in lines)
{
ListOFDescription.Add(S);
Console.WriteLine(S);
}
NewString += ListOFDescription;
break;
case "StartUpdateDescription$":
//Console.WriteLine(Environment.NewLine);
continue;
case "FinishUpdateDescription$":
// Console.WriteLine(Environment.NewLine);
continue;
default:
textInBetween.Add(line);
//Console.WriteLine(line);
break;
}
}
}
}
}
}
Text inside start and finish expression must be in a list of string array.
text inside startupdatedescription and finishupdatedescription must be in a string.
.

One way to do it is using regular expression https://dotnetfiddle.net/pxBAMv

GetExtension method error

I'm getting this error:
would not find a GetExtension method
Code:
public static void Main()
{
string[] arr = {"abc.txt", "asd.TXT","bvc.pdf","fgd.txt","hss.pdf","djhd.xml"};
var arrp = arr.Select(file=>Path.GetExtension(file).TrimStart('.').ToLower()).GroupBy(x=>x,(ext,extcnt)=>new
{
Extension = ext,
count=extcnt.Count()
});
foreach(var v in arrp)
{
Console.WriteLine("{0} files(s) with {1} Extension", v.Count,v.Extension );
Console.ReadLine();
}
}
How can I fix it?

First check, do you have added the using statment? using System.IO;
Second change your code line:
Console.WriteLine("{0} files(s) with {1} Extension", v.Count, v.Extension);
to:
Console.WriteLine("{0} files(s) with {1} Extension", v.count, v.Extension);
i had created a new console application. This example works in my enviroment:
using System;
using System.IO;
using System.Linq;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string[] arr = { "abc.txt", "asd.TXT", "bvc.pdf", "fgd.txt", "hss.pdf", "djhd.xml" };
var arrp = arr.Select(file => Path.GetExtension(file).TrimStart('.').ToLower()).GroupBy(x => x, (ext, extcnt) => new
{
Extension = ext,
count = extcnt.Count()
});
foreach (var v in arrp)
{
Console.WriteLine("{0} files(s) with {1} Extension", v.count, v.Extension);
Console.ReadLine();
}
}
}
}
i get this result:
Important: this is a console application! not a asp.net application! (you have added the asp.net tag.. )

C#: read text file separated by additional newline character

I have some sql commands that are separated by an additional newline character:
ALTER TABLE XXX
ALTER COLUMN xxx real
ALTER TABLE YYY
ALTER COLUMN yyy real
ALTER TABLE ZZZ
ALTER COLUMN zzz real
I've tried reading the file by using an array of character separators such as the following,
new char[] { '\n', '\r'}
inside this method:
private static List<string> ReadFile(string FileName, char[] seps)
{
if (!File.Exists(FileName))
{
Console.WriteLine("File not found");
return null;
}
using (StreamReader sr = new StreamReader(FileName, Encoding.Default))
{
string content = sr.ReadToEnd();
return content.Split(seps, StringSplitOptions.RemoveEmptyEntries).ToList();
}
}
However, this doesn't seem to be working. I would like to have each command represented by a separate string. How can I do this?

Why not use File.ReadAllLines()?
private static List<string> ReadFile(string FileName)
{
if (!File.Exists(FileName))
{
Console.WriteLine("File not found");
return null;
}
var lines = File.ReadAllLines(FileName);
return lines.ToList();
}
This will automatically read and split your file by newlines.
If you want to filter out empty lines, do this:
var nonEmpty = ReadFile(path).Where(x => !string.IsNullOrEmpty(x)).ToList();
Side note, I would change your if statement to throw an exception if the file cannot be found.
if (!File.Exists(FileName))
{
throw new FileNotFoundException("Can't find file");
}

You can filter the examples. When I read them in, the empty lines had a length 1 and its char value said 131 for some reason. So I just filtered by length > 1
void Main()
{
var results = ReadFile(#"C:\temp\sql.txt", new char[]{'\n'});
Console.WriteLine(results.Count);
foreach (var result in results)
{
Console.WriteLine(result);
}
}
private static List<string> ReadFile(string FileName, char[] seps)
{
if (!File.Exists(FileName))
{
Console.WriteLine("File not found");
return null;
}
using (StreamReader sr = new StreamReader(FileName, Encoding.Default))
{
string content = sr.ReadToEnd();
return content.Split(seps, StringSplitOptions.RemoveEmptyEntries).Where (c => c.Length > 1).ToList();
}
}

Try This:
private static List<string> ReadFile(string FileName)
{
List<string> commands = new List<string>();
StringBuilder command = new StringBuilder();
if (!File.Exists(FileName))
{
Console.WriteLine("File not found");
return null;
}
foreach (var line in File.ReadLines(FileName))
{
if (!String.IsNullOrEmpty(line))
{
command.Append(line + "\n");
}
else
{
commands.Add(command.ToString());
command.Clear();
}
}
commands.Add(command.ToString());
return commands;
}

If you are sure you'll always have \r\n line endings, you can use:
var commands = content.Split(new []{"\r\n\r\n"}, StringSplitOptions.RemoveEmptyEntries);
Otherwise, try using regex:
var commands = Regex.Split(content, #"\r?\n\r?\n")

Thank you everyone for your answers. I ended up going with this helper method:
private static List<string> GetCommands(string location)
{
List<string> ret = new List<string>();
List<string> tmp = ReadFile(location, new string[] { "\r\n\r\n"});
for (int i = 0; i < tmp.Count; i++)
{
string rem = tmp[i].Replace("\r", "");
ret.Add(rem);
}
return ret;
}
As an aside, the equivalent is so much easier in Python. For example, what I'm trying to do can be expressed in these three lines:
with open('commands.txt', 'r') as f:
content = f.read()
commands = [ command for command in content.split('\n\n') ]

C# - Assign ConsoleKey then reassign using ConsoleKeyInfo

What I'm trying to accomplish is have a ConsoleKey assigned to a variable then using ConsoleKeyInfo to modify the variable.
I'm getting errors saying Cannot convert source type 'System.ConsoleKey' to target type 'System.ConsoleKeyInfo'.
The reasoning behind this is I wish to have the user be able to reprogram the keys used inside the application.
I have this so far;
public static ConsoleKeyInfo keyboardkeynorth;
keyboardkeynorth = Console.ReadKey();
This works, but it doesn't allow me to start the program with keyboardkeynorth already set to ConsoleKey.W.
Elsewhere in the program I would call keyboardkeynorth to be used as a ConsoleKey
This may be simple but it seems to be eluding me.

Realizing this is a short 3+ years after you asked...
public static ConsoleKeyInfo keyboardkeynorth =
new ConsoleKeyInfo('W', ConsoleKey.W, false, false, false);
And don't you want "north" to be 'N' initially? ;^)
It's a strange, verbose constructor, but does what you appear to be asking.

Here is a complete, and simple, program to show you how you might do this. I say simple because it doesn't take into consideration CTRL, ALT, or SHIFT -- and based on how I gather the custom key info you wouldn't even be able to set those because I'm using ReadKey. But you'll get the idea.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
namespace ConsoleApplication23
{
class Program
{
private static ConsoleKeyInfo keyAction1, keyAction2, keyAction3;
static void Main(string[] args)
{
InitializeKeyActions();
Console.Write("Do you want a new key action for #1? ");
var result = Console.ReadKey();
if (result.Key != ConsoleKey.Enter) { UpdateKeyInfo("keyAction1", result); }
}
private static void UpdateKeyInfo(string keyName, ConsoleKeyInfo result)
{
var propertyInfo = typeof(Program).GetField(keyName, BindingFlags.NonPublic | BindingFlags.Static);
if (propertyInfo == null) { return; }
var key = result.KeyChar;
propertyInfo.SetValue(null, new ConsoleKeyInfo(key, (ConsoleKey)key, false, false, false));
StringBuilder keyActions = new StringBuilder();
foreach (var line in File.ReadAllLines("keyactions.ini"))
{
var kvp = line.Split(new char[] { ':' }, StringSplitOptions.RemoveEmptyEntries);
if (kvp[0] != keyName)
{
keyActions.AppendLine(line);
continue;
}
keyActions.AppendLine(string.Format("{0}: {1}", kvp[0], result.KeyChar));
}
File.WriteAllText("keyactions.ini", keyActions.ToString());
}
private static void InitializeKeyActions()
{
if (!File.Exists("keyactions.ini"))
{
StringBuilder keyActions = new StringBuilder();
keyActions.AppendLine("keyAction1: A");
keyActions.AppendLine("keyAction2: B");
keyActions.AppendLine("keyAction3: C");
File.WriteAllText("keyactions.ini", keyActions.ToString());
}
foreach (var line in File.ReadAllLines("keyactions.ini"))
{
var kvp = line.Split(new char[] { ':' }, StringSplitOptions.RemoveEmptyEntries);
var propertyInfo = typeof(Program).GetField(kvp[0], BindingFlags.NonPublic | BindingFlags.Static);
if (propertyInfo == null) { continue; }
var key = kvp[1].Trim()[0];
propertyInfo.SetValue(null, new ConsoleKeyInfo(key, (ConsoleKey)key, false, false, false));
}
}
}
}

How to delete a line having line number using c#?

My file named as test.txt contains
This document is divided into about 5 logical sections starting with a feature and structure overview, followed by an overview of built in column and cell types. Next is an overview of working with data, followed by an overview of specific major features. Lastly, a “best practice” section concludes the main part of this document.
Now i want to delete 2nd line of the file.
How to do it using c#?
Thanks in advance.
Naveenkumar

List<string> lines = File.ReadAllLines(#"filename.txt").ToList();
if(lines.Count>lineNum){
lines.RemoveAt(lineNum);
}
File.WriteAllLines(#"filename.txt",lines.ToArray());

You can acheive this by splitting the text by \n and then using LINQ to select the lines you want to keep, and re-joining them.
var lineNum=5;
var lines=File
.ReadAllText(#"src.txt")
.Split('\n');
var outTxt=String
.Join(
"\n",
lines
.Take(lineNum)
.Concat(lines.Skip(lineNum+1))
.ToArray()
);

Here's a pretty efficient way to do it.
FileInfo x = new FileInfo(#"path\to\original");
string xpath = x.FullName;
FileInfo y = new FileInfo(#"path\to\temporary\new\file");
using (var reader = x.OpenText())
using (var writer = y.AppendText())
{
// write 1st line
writer.WriteLine(reader.ReadLine());
reader.ReadLine(); // skip 2nd line
// write all remaining lines
while (!reader.EndOfStream)
{
writer.WriteLine(reader.ReadLine());
}
}
x.Delete();
y.MoveTo(xpath);

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace rem2ndline
{
class Program
{
static void Main(string[] args)
{
string inPath = #"c:\rem2ndline.txt";
string outPath = #"c:\rem2ndlineresult.txt";
StringBuilder builder = new StringBuilder();
using (FileStream fso = new FileStream(inPath, FileMode.Open))
{
using (StreamReader rdr = new StreamReader(fso))
{
int lineCount = 0;
bool canRead = true;
while (canRead)
{
var line = rdr.ReadLine();
lineCount++;
if (line == null)
{
canRead = false;
}
else
{
if (lineCount != 2)
{
builder.AppendLine(line);
}
}
}
}
}
using(FileStream fso2 = new FileStream(outPath, FileMode.OpenOrCreate))
{
using (StreamWriter strw = new StreamWriter(fso2))
{
strw.Write(builder.ToString());
}
}
}
}
}

Here's what I'd do. The advantage is that you don't have to have the file in memory all at once, so memory requirements should be similar for files of varying sizes (as long as the lines contained in each of the files are of similar length). The drawback is that you can't pipe back to the same file - you have to mess around with a Delete and a Move afterwards.
The extension methods may be overkill for your simple example, but those are two extension methods I come to rely on again and again, as well as the ReadFile method, so I'd typically only have to write the code in Main().
class Program
{
static void Main()
{
var file = #"C:\myFile.txt";
var tempFile = Path.ChangeExtension(file, "tmp");
using (var writer = new StreamWriter(tempFile))
{
ReadFile(file)
.FilterI((i, line) => i != 1)
.ForEach(l => writer.WriteLine(l));
}
File.Delete(file);
File.Move(tempFile, file);
}
static IEnumerable<String> ReadFile(String file)
{
using (var reader = new StreamReader(file))
{
while (!reader.EndOfStream)
{
yield return reader.ReadLine();
}
}
}
}
static class IEnumerableExtensions
{
public static IEnumerable<T> FilterI<T>(
this IEnumerable<T> seq,
Func<Int32, T, Boolean> filter)
{
var index = 0;
foreach (var item in seq)
{
if (filter(index, item))
{
yield return item;
}
index++;
}
}
public static void ForEach<T>(
this IEnumerable<T> seq,
Action<T> action)
{
foreach (var item in seq)
{
action(item);
}
}
}