I'm making a program that writes a list of student objects to a text file and needs to be saved, I could either simply overwrite the contents of the file or delete the contents and rewrite the new list. This is the code I've tried using after some searching,
private void saveTSMI_Click(object sender, EventArgs e)
{
if (lstStudNames.Items.Count != 0)
{
SaveFileDia.Filter = "Text Files | *.txt";
if (SaveFileDia.ShowDialog() == DialogResult.OK)
{
//Clear the file
File.WriteAllText(SaveFileDia.FileName, string.Empty);
//Put all the student info into a string
foreach (Stud student in StudentList)
{
StudentInfoHolder += "Name: " + student.Name + Environment.NewLine +
"Subject: " + student.Subject + Environment.NewLine +
"Age: " + student.age + Environment.NewLine +
"Grade: " + student.Grade + Environment.NewLine
+ Environment.NewLine;
}
Clipboard.SetText(StudentInfoHolder);
File.WriteAllText(SaveFileDia.FileName, StudentInfoHolder);
}
}
else
{
MessageBox.Show("Nothing to save");
}
I've seen that File.WriteAllText() is meant to overwrite the file but nothing is overwritten when the program is saved.
You have to either reset the StudentInfoHolder class member before the foreach loop, or even better, use a local string variable in combination with String.Format method like this:
string studentInfoHolder;
foreach (Stud student in StudentList)
{
studentInfoHolder +=
string.Format("Name: {0}\r\nSubject: {1}\r\nAge: {2}\r\nGrade: {3}",
student.Name, student.Subject, student.age, student.Grade);
}
File.WriteAllText(SaveFileDia.FileName, studentInfoHolder);
Also, you're right that File.WriteAllText overwrites the file content, so this line is useless:
File.WriteAllText(SaveFileDia.FileName, string.Empty);
Update
As #kevin correctly pointed out, it is more efficient to use StringBuilder in the loop instead of the string concatenation:
StringBuilder studentInfoHolder;
foreach (Stud student in StudentList)
{
studentInfoHolder.AppendFormat("Name: {0}\r\nSubject: {1}\r\nAge: {2}\r\nGrade: {3}",
student.Name, student.Subject, student.age, student.Grade);
}
File.WriteAllText(SaveFileDia.FileName, studentInfoHolder.ToString());
Try something more like the following. It avoids opening the file twice, and string concatenation, which is not a great idea with immutable strings.
// This line over-writes the file if it exists, or otherwise creates it.
using (TextWriter fileWriter = new StreamWriter(SaveFileDia.FileName, append: false))
{
foreach (Stud student in StudentList)
{
fileWriter.WriteLine($"Name: {student.Name}");
fileWriter.WriteLine($"Subject: {student.Subject}");
fileWriter.WriteLine($"Age: {student.age}");
fileWriter.WriteLine($"Grade: {student.Grade}");
fileWriter.WriteLine();
}
}
There's no good reason to buffer all that in memory before writing it to the file. It's easier to open the file by calling File.CreateText, and then write each line to it, like this:
private void saveTSMI_Click(object sender, EventArgs e)
{
if (lstStudNames.Items.Count == 0)
{
MessageBox.Show("Nothing to save");
return;
}
SaveFileDia.Filter = "Text Files | *.txt";
if (SaveFileDia.ShowDialog() != DialogResult.OK)
{
return;
}
// Create the file (overwrite if it already exists),
// and write each student record.
using (var outFile = File.CreateText(SaveFileDia.FileName))
{
foreach (Stud student in StudentList)
{
outFile.WriteLine("Name: " + student.Name);
outFile.WriteLine("Subject: " + student.Subject);
outFile.WriteLine("Age: " + student.age);
outFile.WriteLine("Grade: " + student.Grade);
}
}
}
I also refactored your code a bit, reversing the logic on those two tests up front so as to reduce the nesting in your code.
Update after comment
If you really want a string to contain all that stuff, then you can modify the above to do it pretty easily. Replace the loop that writes to file with this one that uses a StringWriter:
// Create a StringWriter to hold the data, and write each line.
using (var sWriter = new StringWriter())
{
foreach (Stud student in StudentList)
{
sWriter.WriteLine("Name: " + student.Name);
sWriter.WriteLine("Subject: " + student.Subject);
sWriter.WriteLine("Age: " + student.age);
sWriter.WriteLine("Grade: " + student.Grade);
}
// write the data to the file
StudentInfoHolder = sWriter.ToString();
File.WriteAllText(SaveFileDia.FileName, StudentInfoHolder);
}
Related
I need to fill a text file with information about workers. Then I need to read from the file and search for an ID that user tries to find. For example my file contains ids 1,2,3 and if I try to find id 3 and it matches, then this worker's all information is written in console. Otherwise it writes a text A worker cannot be found.
using System;
using System.IO;
class Program
{
static void Main(string[] args)
{
string file = "C:\\Temp\\registery.txt";
FileStream fOutStream = File.Open(file, FileMode.Append, FileAccess.Write);
StreamWriter sWriter = new StreamWriter(fOutStream);
int[] id = { 1, 2, 3 };
string[] name = { "John", "Carl", "Thomas" };
float[] salary = { 3500, 4800, 2100 };
for (int i = 0; i < id.Length; i++)
{
sWriter.WriteLine(id[i] + " " + name[i] + " " + salary[i]);
}
sWriter.Flush();
sWriter.Close();
FileStream fInStream = File.OpenRead(file);
StreamReader sReader = new StreamReader(fInStream);
int id2;
Console.WriteLine("Type worker's id");
id2 = int.Parse(Console.ReadLine());
bool a;
a = sReader.ReadToEnd().Contains(id2);
Console.WriteLine(a);
sReader.Close();
}
}
If you want to create a text file to be searchable, it should be delimited by a separator like comma /TAB
so modify your code:
sWriter.WriteLine(id[i] + "," + name[i] + "," + salary[i]);
To search your text file by id/name/..whatever and use AND/OR, you can use the method described here:
How would I convert data in a .txt file into xml? c#
BTW: Re-factor your code to create the file in a separate method, and the search in other one.
I found a solution myself to my problem and it worked good enough. It might not be the best solution. I removed bool things and I replaced the whole thing with this:
string line;
while ((line = sReader.ReadLine()) != null)
{
if (line.Contains("id: " + id2))
{
Console.WriteLine(line);
break;
}
else if ((line = sReader.ReadLine()) == null)
{
Console.WriteLine("Worker not found with id " + id2);
}
}
And I fixed the upper for loop to look like this:
sWriter.WriteLine("id: " + id[i] + " name: " + name[i] + " salary: " + salary[i]);
Hello I'm trying to add a list in a file using interface, but I can add only last item of list in it? Whats wrong?
I think I'm ok with interface.
//interface
interface IRuajtshem
{
void Ruaj();
}
I think here is the problem.
//class
public class Student : IRuajtshem
{
protected int ID;
protected string emri;
protected string mbiemri;
...
...
...
public void Ruaj()
{
string path = #"C:\\...\\...\\text.txt";
if (File.Exists(path))
{
File.Delete(path);
}
else if (!File.Exists(path))
File.Create(path).Close();
var f = File.AppendText(path);
f.WriteLine(Studenti + " " + Studentii + " " + Studentiii);
f.Close();
}
}
And finally the list ...
//#Main()
List<Student> student = new List<Student>()
{
new Student(1, "Name", "Surname"),
new Student(2, "name", "Surname"),
new Student(3, "Name", "surname"),
new Student(4, "name", "surname")
};
foreach (Student st in student)
{
st.Ruaj();
Console.WriteLine();
}
You keep deleting and recreating the file. Try this instead:
public void Ruaj()
{
string path = #"C:\\...\\...\\text.txt";
using (var f = File.AppendText(path))
{
f.WriteLine(Studenti + " " + Studentii + " " + Studentiii);
}
}
This is the part of your code that kept "resetting" the file:
if (File.Exists(path))
{
File.Delete(path); // deletes file if it exists
}
else if (!File.Exists(path))
File.Create(path).Close(); // creates empty file if doesnt exist
And I think that creating an empty file is unneeded as well, because AppendText will create the file for you if it doesn't exist, and not throw an error:
Creates a StreamWriter that appends UTF-8 encoded text to an existing file, or to a new file if the specified file does not exist.
From here.
Another method you might want to check out is AppendAllText which gets a path and a string, and does all the dirty work for you in one line. Just need to make sure your string ends with "\r\n" if you ever want a line break.
This is because you are deleting the file if it exists:
if (File.Exists(path))
{
File.Delete(path);
}
You should open the file instead of deleting it.
So I want to put certain lines into a text box, say I use the "Search Function" to search transaction ID, it would look through the transactions.txt file and find the transaction ID and Read the 6 lines under it which show the transactions Details, once found this would then go to a the listbox which then you could edit the transaction.
I was wondering would you use loops and arrays to do this, and could someone show me how, Thank you!
Heres my current code:
//Creates a textfile with details of the transaction
public void CreateFile()
{
StreamWriter outputFile;
outputFile = File.AppendText("Transactions.txt");
outputFile.WriteLine("Investor :" +" " + InvestorNameLabel.Text);
outputFile.WriteLine("Initial Amount" + " " +AmountLabel.Text);
outputFile.WriteLine("Date Invested" +" " +DateLabel.Text);
outputFile.WriteLine("Period Chosen" + " "+DaysInvestedLabel.Text);
outputFile.WriteLine("Rate Chosen" + " " + RateLabel.Text);
outputFile.WriteLine("Total Interest" + " " +InterestAmountLabel.Text);
outputFile.WriteLine("Transaction Number :" + " " + TransactionIDLabel.Text);
outputFile.Close();
MessageBox.Show("Transaction file for Transaction: " + TransactionIDLabel.Text + " " +"Was Created", "Transaction File");
}
//puts all transactions in listbox
//needs to be able to find certain transactions
private void button1_Click(object sender, EventArgs e)
{
using (StreamReader sr = new StreamReader("transactions.txt"))
{
string line;
while ((line = sr.ReadLine()) != null)
{
listBox1.Items.Add(line);
}
}
}
Try This:
string ID = "23";
bool idFound=false;
int count = 0;
foreach (var line in File.ReadLines("transactions.txt"))
{
if (idFound && count < 6)
{
listBox1.Items.Add(line);
count++;
}
if(line.Contains(ID))//if you wantto match exactly use if(line.Equals(ID))
{
idFound = true;
}
}
I have been doing this for a university project and have run into a problem. I have managed to load multiple lines from a file but I am unable to save them back to a file. I can save a single string to the file, which is the last string processed but that is it. I may be doing it completely wrong by performing a loop, but I cant think of any other way to do it. The coding for the savefile section is as follows:
case "s":
case "8":
{
int savecount = 0;
string savestring = "";
//Clear the text file ready to be saved
using (FileStream fs = File.Create("billing.txt"))
{
}
while (savecount != CustomerCount)
{
using (StreamWriter save = new StreamWriter("billing.txt"))
{
//Create the string to save to the file
savestring = CustomerNumber[savecount] + ","
+ CustomerName[savecount] + ","
+ Address[savecount] + ","
+ RateScheme[savecount] + ","
+ PeakKWH[savecount] + ","
+ OffPeakKWH[savecount] + ","
+ StandardKWH[savecount];
Console.WriteLine(savestring);
save.WriteLine(savestring);
savecount++;
Console.ReadLine();
}
}
Console.WriteLine("All data saved successfully");
Console.ReadLine();
break;
}
Not sure where to go from here. Any help would be appreciated
You should open the file for saving before the loop. E.g.
using (StreamWriter save = new StreamWriter("billing.txt")) {
while (savecount != CustomerCount) {
// rest of your code here
At the moment, you are opening the file in each loop, writing a line out. Then re-opening it (and losing the data already written).
As pointed out in the comments, you don't need to call File.Create. By default the StreamWriter will overwrite the existing file.
You need the while loop inside the using { } As it is you're overwriting your data each time, leaving the last item in your file when you look at it:
using (StreamWriter save = new StreamWriter("billing.txt"))
{
while (savecount != CustomerCount)
{
//Create the string to save to the file
string savestring = CustomerNumber[savecount] + ","
+ CustomerName[savecount] + ","
+ Address[savecount] + ","
+ RateScheme[savecount] + ","
+ PeakKWH[savecount] + ","
+ OffPeakKWH[savecount] + ","
+ StandardKWH[savecount];
Console.WriteLine(savestring);
save.WriteLine(savestring);
savecount++;
Console.ReadLine();
}
}
What You are doing wrong is, you are opening the file in each iteration of while, writing a line in file and Then again re-opening the file and overwriting the contents. You can rechange your code
using (StreamWriter save = new StreamWriter("billing.txt"))
{
while (savecount != CustomerCount)
{
// rest of string formation of saveString logic and save.WriteLine(savestring); goes here
.....
}
}
I think you can use a simple code also where you can save all your input string in an List and use File.WriteAllLines function as
{
....
List<string> Customers = new List<string>();
for (savecount = 0; savecount < CustomerCount; savecount++)
{
//Create the string to save to the file
Customers.Add( CustomerNumber[savecount] + "," + CustomerName[savecount] + "," + Address[savecount] + "," + RateScheme[savecount] + "," + PeakKWH[savecount] + "," + OffPeakKWH[savecount] + "," + StandardKWH[savecount]);
Console.WriteLine(Customers[savecount]);
}
string filePath = "billing.txt"; // This is your file path where all the contents are to be written
File.WriteAllLines(filePath, Customers);
..........
}
You need:
using (StreamWriter save = new StreamWriter("billing.txt")) {
while (savecount != CustomerCount) {
You have to open file before loop because opening inside deletes all previous data written in that, also it takes some time for opening.
However you can open file inside loop, but you need to set append file, it would be:
StreamWriter save = new StreamWriter("billing.txt", true)
This option is slower and you may need to clear file before opening in append mode, so it isn't the best option.
I am using the code below start at a path (root) provided by a GET variable and recursively go into every sub folder and display it's contents as list items. The path I'm using has about 3800 files and 375 sub folders. I takes about 45 seconds to render the page, is there any way I can cut this time down as this is unacceptable for my users.
string output;
protected void Page_Load(object sender, EventArgs e) {
getDirectoryTree(Request.QueryString["path"]);
itemWrapper.InnerHtml = output;
}
private void getDirectoryTree(string dirPath) {
try {
System.IO.DirectoryInfo rootDirectory = new System.IO.DirectoryInfo(dirPath);
foreach (System.IO.DirectoryInfo subDirectory in rootDirectory.GetDirectories()) {
output = output + "<ul><li><a>" + Regex.Replace(subDirectory.Name, "_", " ");
if (subDirectory.GetFiles().Length != 0 || subDirectory.GetDirectories().Length != 0) {
output = output + " +</a>";
} else {
output = output + "</a>";
}
getDirectoryTree(subDirectory.FullName);
if (subDirectory.GetFiles().Length != 0) {
output = output + "<ul>";
foreach (System.IO.FileInfo file in subDirectory.GetFiles()) {
output = output + "<li><a href='" + file.FullName + "'>" + file.Name + "</a></li>";
}
output = output + "</ul>";
}
output = output + "</li></ul>";
}
} catch (System.UnauthorizedAccessException) {
//This throws when we don't have access.
}
}
You should use System.Text.StringBuilder (Good performance) instead of string concatenate(Immutable) Bad performance.
You should use normal string replace function is not using complex search. subDirectory.Name.replace("_", " ");
Main reason for slowness in your code is most likely multiple calls to GetFiles and GetDirectories. You are calling them over and over again in if conditions as well as in your initial lookups. You only need the counts only once. Also, adding strings aren't helping the cause.
Following code was able to run through my simple usb-drive in 300ms and return with over 400 folders and 11000 files. On slow network drive, it was able to return in 9 seconds for 4000 files in 300 folders. It can probably be further optimized with Parallel.ForEach during recursion.
protected void Page_Load(object sender, EventArgs e) {
itemWrapper.InnerHtml = GetDirectory(Request.QueryString["path"]);
}
static string GetDirectory(string path)
{
StringBuilder output = new StringBuilder();
var subdir = System.IO.Directory.GetDirectories(path);
var files = System.IO.Directory.GetFiles(path);
output.Append("<ul><li><a>");
output.Append(path.Replace("_", " "));
output.Append(subdir.Length > 0 || files.Length > 0 ? "+</a>" : "</a>");
foreach(var sb in subdir)
{
output.Append(GetDirectory(sb));
}
if (files.Length > 0)
{
output.Append("<ul>");
foreach (var file in files)
{
output.AppendFormat("<li>{1}</li>", file, System.IO.Path.GetFileName(file));
}
output.Append("</ul>");
}
output.Append("</ul>");
return output.ToString();
}