I am reading strings from a binary file. Each string is null-terminated. Encoding is UTF-8. In python I simply read a byte, check if it's 0, append it to a byte array, and continue reading bytes until I see a 0. Then I convert byte array into a string and move on. All of the strings were read correctly.
How can I read this in C#? I don't think I have the luxury of simply appending bytes to an array since the arrays are fixed size.
Following should get you what you are looking for. All of text should be inside myText list.
var data = File.ReadAllBytes("myfile.bin");
List<string> myText = new List<string>();
int lastOffset = 0;
for (int i = 0; i < data.Length; i++)
{
if (data[i] == 0)
{
myText.Add(System.Text.Encoding.UTF8.GetString(data, lastOffset, i - lastOffset));
lastOffset = i + 1;
}
}
I assume you're using a StreamReader instance:
StringBuilder sb = new StringBuilder();
using(StreamReader rdr = OpenReader(...)) {
Int32 nc;
while((nc = rdr.Read()) != -1) {
Char c = (Char)nc;
if( c != '\0' ) sb.Append( c );
}
}
You can either use a List<byte>:
List<byte> list = new List<byte>();
while(reading){ //or whatever your condition is
list.add(readByte);
}
string output = Encoding.UTF8.GetString(list.ToArray());
Or you could use a StringBuilder :
StringBuilder builder = new StringBuilder();
while(reading){
builder.Append(readByte);
}
string output = builder.ToString();
If your "binary file" only contains null terminated UTF8 strings, then for .NET it isn't a "binary file" but just a text file because null characters are characters too. So you could just use a StreamReader to read the text and split it on the null characters.
(Six years later "you" would presumably be some new reader and not the OP.)
A one line (ish) solution would be:
using (var rdr = new StreamReader(path))
return rdr.ReadToEnd().split(new char[] { '\0' });
But that will give you a trailing empty string if the last string in the file was "properly" terminated.
A more verbose solution that might perform differently for very large files, expressed as an extension method on StreamReader, would be:
List<string> ReadAllNullTerminated(this System.IO.StreamReader rdr)
{
var stringsRead = new System.Collections.Generic.List<string>();
var bldr = new System.Text.StringBuilder();
int nc;
while ((nc = rdr.Read()) != -1)
{
Char c = (Char)nc;
if (c == '\0')
{
stringsRead.Add(bldr.ToString());
bldr.Length = 0;
}
else
bldr.Append(c);
}
// Optionally return any trailing unterminated string
if (bldr.Length != 0)
stringsRead.Add(bldr.ToString());
return stringsRead;
}
Or for reading just one at a time (like ReadLine)
string ReadNullTerminated(this System.IO.StreamReader rdr)
{
var bldr = new System.Text.StringBuilder();
int nc;
while ((nc = rdr.Read()) > 0)
bldr.Append((char)nc);
return bldr.ToString();
}
Related
I have a text file which contain of lots of information, but i only want to show the serial number of the text file. I am able to read and show the whole line of the serial number in label, but i only required the serial number in the format of ["BcXXXXX"]. Anyone would able to guide through?
string path = #"D:\Sample.txt";
StringBuilder buffer = new StringBuilder();
using (StreamReader sr = new StreamReader(path))
{
while (sr.Peek() >= 0)
{
String str = sr.ReadLine();
if (Regex.IsMatch(str, "Bc"))
buffer.Append(str);
string s = buffer.Append(str);
int start = s.IndexOf("["Bc") + 1;
int end = s.IndexOf(""]" , start);
string result = s.Substring(start, end - start);
label2.Text = result.ToString();
}
string serialNumber = System.IO.File.ReadLines(#"D:\Sample.txt")
.Select(line =>
{
var match = System.Text.RegularExpressions.Regex.Match(line, #"^\[""(.*)""\]$");
return match.Success ? match.Groups[1].Value : null;
}).FirstOrDefault(sn => sn != null);
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());
}
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] : "";
}
I want to read words in a text file of a line separated by commas in c sharp.
For example, I want to read this line:
9/10/2011 10:05,995.4,998.8,995.4,997.5,118000
and get the values: 9/10/2011 10:05, 995.4, 998.8, 995.4, 997.5 and 118000.
Next, I also need to change the format of the date to MMddYYYY, and of the time to HHmmss (e.g. 100500).
I am using this code for reading is there anything wrong
private void button1_Click(object sender, EventArgs e)
{
StreamReader reader1 = File.OpenText(Path1);
string str = reader1.ReadToEnd();
reader1.Close();
reader1.Dispose();
// File.Delete(Path1);
string[] Strarray = str.Split(new char[] { Strings.ChrW(7) });
int abc = Strarray.Length - 1;
int xyz = 0;
bool status = true;
while (xyz <= abc)
{
try
{
status = true;
string[] strarray1 = Strarray[xyz].Split(",".ToCharArray());
string SecName = strarray1[0];
int a2 = 0;
while (status) //If the selected list is empty or the text file has selected name this will execute
{
status = false;
string SecSym = strarray1[1];
int DT = int.Parse(strarray1[2]);
int TM = int.Parse(strarray1[3]);
float O = float.Parse(strarray1[2]);
float H = float.Parse(strarray1[3]);
float L = float.Parse(strarray1[4]);
float C = float.Parse(strarray1[5]);
double OI = double.Parse(Convert.ToString(0));
float V = float.Parse(strarray1[6]);
// string a = string.Concat(SecName, ",",SecSym,",", DT, ",", TM, ",", O, ",", H, ",", L);
//writer.WriteLine(a);
}
}
catch
{ }
}
}
}
.Net comes with a ready CSV parser you can use to get your data. It's a part of VB.net, but you can easily use it in C# by adding a reference to the assembly Microsoft.VisualBasic (it's OK, honesly), and a using statement: using Microsoft.VisualBasic.FileIO;.
The code should be simple to understand:
List<String[]> fileContent = new List<string[]>();
using(FileStream reader = File.OpenRead(#"data.csv")) // mind the encoding - UTF8
using(TextFieldParser parser = new TextFieldParser(reader))
{
parser.TrimWhiteSpace = true; // if you want
parser.Delimiters = new[] { "," };
parser.HasFieldsEnclosedInQuotes = true;
while (!parser.EndOfData)
{
string[] line = parser.ReadFields();
fileContent.Add(line);
}
}
CSV is fairly simple, but it may contain quoted values with commas and newlines, so using Split isn't the best option.
Use the String.Split method to get an array of strings:
string[] ar = line.Split(',')
This should get you started.
using System;
using System.IO;
public class Sample
{
public static void Main() {
using (StreamReader reader = new StreamReader("yourfile.txt")) {
string line = null;
while (null != (line = reader.ReadLine())) {
string[] values = line.Split(',');
DateTime date = DateTime.Parse(values[0];
float[] numbers = new float[values.Length - 1];
for (int i = 1; i < values.Length - 1; i++)
numbers[i - 1] = float.Parse(values[i]);
// do stuff with date and numbers
}
}
}
}
I have also posted a simple CsvReader class which may be helpful for you.
For a quick and simple solution, you can stream through the file and parse each line using String.Split like this:
using (var sr = File.OpenText("myfile.csv"))
{
string line;
while ((line = sr.ReadLine()) != null)
{
var fields = line.Split(',');
var date = DateTime.Parse(fields[0].Trim());
var value1 = fields[0].Trim();
}
}
However, this appraoch if fairly error prone, for a more robust solution check out the CsvReader project, it's excellent for parsing CSV files like this. It will handle field values with commas, trimming spaces before and after fields, and much more.
If you need to parse a date string from a format not recognised by DateTime.Parse, try using DateTime.ParseExact instead.
For 1st part of your task use Split method with , as separator. To convert string datetime from one format to another you need to convert that string to datetime(DateTime.Parse, DateTime.ParseExact) and then convert to final format using DateTime.ToString method.
rows contain your output
StreamReader sStreamReader = new StreamReader("File Path");
string AllData = sStreamReader.ReadToEnd();
string[] rows = AllData.Split(",".ToCharArray());
Please, help me understand, what's wrong with this code. (I am trying to build a string, taking parts of it line by line from a text file).
I get a runtime error "In the instance of the object reference not set to an object" on the line strbuild.Append(str);
StreamReader reader = new StreamReader("buf.txt", System.Text.Encoding.ASCII);
StringBuilder strbuild = new StringBuilder();
strbuild = null;
while (reader.Peek() >= 0)
{
string str = null;
str = reader.ReadLine().ToString();
string segment = str.Substring(0, 1);
if (segment == "A")
{
strbuild.Append(str); //here i get an error
}
else if (segment == "B")
{
strbuild.Append("BET");
}
}
printstr = strbuild.ToString();
reader.Close();
MessageBox.Show(printstr);
Look at these lines:
StringBuilder strbuild = new StringBuilder();
strbuild = null;
What do you expect to happen when you then call strbuild.Append(...)? Why are you setting strbuild to null at all?
You seem to be fond of two-line variable initialization - here's another example:
string str = null;
str = reader.ReadLine().ToString();
This would be more easily readable as just:
string str = reader.ReadLine();
(ReadLine already returns a string, so you don't need to call ToString() on the result.)
However, I do suggest that you use a using statement for the StreamReader - otherwise when an exception is thrown, you'll be leaving the reader open.
One nice thing about TextReader.ReadLine() is that it returns null when you're done. You don't need to peek and then read.
Finally, if you're only testing a single character you don't need a substring - just use the string indexer to get a char. So, you could have:
StringBuilder builder = new StringBuilder();
// Consider using File.OpenText
using (StreamReader reader = new StreamReader("buf.txt", Encoding.ASCII))
{
string line;
// Normally side-effect + test is ugly, but this is a common and
// neat idiom
while ((line = reader.ReadLine()) != null)
{
// TODO: What do you want to happen for empty lines?
char segment = str[0];
if (segment == 'A')
{
builder.Append(line);
}
else if (segment == 'B')
{
builder.Append("BET");
}
}
}
MessageBox.Show(builder.ToString());
You are setting the stringbuilder to null after initialization.
Change
StringBuilder strbuild = new StringBuilder();
strbuild = null;
to
StringBuilder strbuild = new StringBuilder();
leaving out the line
strbuild = null;
Change
StringBuilder strbuild = new StringBuilder();
strbuild = null;
to
StringBuilder strbuild = null;
strbuild = new StringBuilder();
or, to prevent this kind of error:
StringBuilder strbuild = new StringBuilder();
There are some many errors within your example, here is a first corrected version:
StringBuilder strbuild = new StringBuilder();
// Put resource into using statements, for deterministic cleanup
using (TextReader reader = new StreamReader("buf.txt", System.Text.Encoding.ASCII))
{
string line;
//Maybe looks a little ugly the first time, but is commonly used to
//process all the lines of a file (.ReadToEnd() can cause memory problems
//on really big files)
while ((line = reader.ReadLine()) != null)
{
//Instead of if, else if, else if, etc just take a switch
//statement. Makes it much easier to read.
switch (line[0])
{
//If you need case insensitivity put both versions of the character
//before your first line of code
case 'A':
case 'a':
strbuild.Append(line);
break;
//Otherwise just use the lower or upper case version you like
case 'B':
strbuild.Append("BET");
break;
}
}
}
//Put the result of the StringBuilder directly into the Show() function
MessageBox.Show(strbuild.ToString());