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C#, Write in a .txt file, without deleting the previous line [duplicate]

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Open existing file, append a single line
(9 answers)
Closed 4 years ago.
Basicly I'm writing a fake malware, which will write in a .txt the Session username of the person which clicked on it. The problem is that when someone execute it will erase the previous lines.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.Text = "Fake Malware";
}
private void Form1_Load(object sender, EventArgs e)
{
string createText = " just clicked on the fake Malware";
File.WriteAllText("//vm-files/users/ngallouj/zig/zig.txt", Environment.UserName + createText + " " + DateTime.Now.ToString("h:mm:ss tt"));
string readText = File.ReadAllText("//vm-files/users/ngallouj/zig/zig.txt");
}
private void zig(object sender, EventArgs e)
{
System.Diagnostics.Process.Start("Link to a warning message on click, nothing important.");
string createText = " just clicked on the fake Malware";
File.WriteAllText("//vm-files/users/ngallouj/zig/zig.txt", Environment.UserName+ createText + " " + DateTime.Now.ToString("h:mm:ss tt"));
string readText = File.ReadAllText("//vm-files/users/ngallouj/zig/zig.txt");
}
}

I think what you are looking for is AppendAllText:
File.AppendAllText("//vm-files/users/ngallouj/zig/zig.txt", "Wow it worked :)");

Here is the fix
private void Form1_Load(object sender, EventArgs e)
{
string createText = " just clicked on the fake Malware";
File.AppendAllText("//vm-files/users/ngallouj/zig/zig.txt", Environment.UserName + createText + " " + DateTime.Now.ToString("h:mm:ss tt"));
string readText = File.ReadAllText("//vm-files/users/ngallouj/zig/zig.txt");
}
private void zig(object sender, EventArgs e)
{
System.Diagnostics.Process.Start("#");
string createText = " just clicked on the fake Malware";
File.AppendAllText("//vm-files/users/ngallouj/zig/zig.txt", Environment.UserName+ createText + " " + DateTime.Now.ToString("h:mm:ss tt"));
string readText = File.ReadAllText("//vm-files/users/ngallouj/zig/zig.txt");
}
}
}

How can I update image in listview in gridview format?

how can i update image in listview in gridview formate using folder path in asp.net in c#?
protected void UpdateButton_Click(object sender, EventArgs e)
{
TextBox ApplicantIdTextBox = (TextBox)RadListView8.FindControl("ApplicantIdTextBox");
FileUpload photoTextBox = (FileUpload)RadListView8.FindControl("photoTextBox");
string fileName1 = Path.GetExtension(ApplicantIdTextBox + photoTextBox.FileName);
string fileSavePath = Server.MapPath("ImageStorage/" + fileName1);
tblPersonalInfo pi = new tblPersonalInfo();
pi.photo = fileName1;
photoTextBox.SaveAs(fileSavePath);
dbcontext.AddTotblPersonalInfoes(pi);
dbcontext.SaveChanges();
}
But it show me error...What can i do?
Server Error in '/HrPayRoll' Application.
Object reference not set to an instance of an object.

I'd rewrite it something like this and then run it in debug mode and see what line the error is on. You were trying to use applicantIdTextBox as a string, although I would have thought that would give a different error:
protected void UpdateButton_Click(object sender, EventArgs e)
{
TextBox applicantIdTextBox = RadListView8.FindControl("ApplicantIdTextBox") as TextBox;
FileUpload photoTextBox = RadListView8.FindControl("photoTextBox") as FileUpload;
if ((applicantIdTextBox != null) && (photoTextBox != null))
{
string fileName = Path.GetExtension(applicantIdTextBox.Text + photoTextBox.FileName);
string fileSavePath = Server.MapPath("ImageStorage/" + fileName);
tblPersonalInfo personalInfo = new tblPersonalInfo();
personalInfo.photo = fileName;
photoTextBox.SaveAs(fileSavePath);
dbcontext.AddTotblPersonalInfoes(personalInfo);
dbcontext.SaveChanges();
}
}

Problems with textboxes and page load in C#

Okay here I have some code from my project at the moment.
Basically the user goes onto the page and their current password is in the password textbox, and their avatar is selected in the droplist.
They can change their password by editing the text in the textbox and change their avatar by selecting a new one from the list. This is then written to the file where this information is kept. It writes to the file okay, but it writes what was initially in the textbox and droplist.
If i comment out these lines in the page load:
avatarDropList.SelectedValue = Session["avatar"].ToString();
newPasswordTextbox.Text = Session["password"].ToString();
It updates the file properly, but this is not what I want as I want the old password displayed there initially as well as the avatar to be selected in the dropbox.
Code below:
public partial class TuitterProfile : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
avatarImage.ImageUrl = "~/images/avatars/" + Session["avatar"] + ".gif";
avatarDropList.SelectedValue = Session["avatar"].ToString();
userNameTextbox.Text = Session["user"].ToString();
newPasswordTextbox.Text = Session["password"].ToString();
}
protected void okButton_Click(object sender, ImageClickEventArgs e)
{
string username = Session["user"].ToString();
string password = Session["password"].ToString();
string newPassword = newPasswordTextbox.Text;
string newAvatar = avatarDropList.SelectedValue;
int allDataReference = -1;
//Each element in the array is a string(Username Password Avatar)
string[] allData = File.ReadAllLines(Server.MapPath("~") + "/App_Data/tuitterUsers.txt");
for (int i = 0; i < allData.Length; i++)
{
string[] user = allData[i].Split(' ');
if (user[0] == username && user[1] == password)
{
allDataReference = i;
}
}
if (allDataReference > -1)
{
Session["avatar"] = newAvatar;
Session["password"] = newPassword;
allData[allDataReference] = username + " " + newPassword + " " + newAvatar;
File.WriteAllLines(Server.MapPath("~") + "/App_Data/tuitterUsers3.txt", allData);
}
}
}

In the ASP.Net page event lifecycle, Page_Load is called on every request. What you are doing here is resetting the value of the TextBox every time the page loads, which will include the time that you press the button to save the profile.
All you need to do is check for the current request being a postback when you set your initial values:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
avatarImage.ImageUrl = "~/images/avatars/" + Session["avatar"] + ".gif";
avatarDropList.SelectedValue = Session["avatar"].ToString();
userNameTextbox.Text = Session["user"].ToString();
newPasswordTextbox.Text = Session["password"].ToString();
}
}

Variable reverting to initialised value

In the following I've taken out irrelevant code. I've created a field called printString. The calculateButton_Click method does a heap of stuff, then I want to send it to a print-friendly page using response.write. However the printString variable doesn't seem to ever stop being "DEFAULT". DEFAULT is all that shows up on my blank page when I click the printButton_Click. Trimmed code below:
public partial class _Default : System.Web.UI.Page
{
private string _printString = "DEFAULT";
protected void Page_Load(object sender, EventArgs e)
{
Response.Buffer = true;
}
protected void calculateButton_Click(object sender, EventArgs e)
{
_printString = "";
_printString = "HARRY POTTER™: THE EXHIBITION Invoice<BR>Today's date: " + DateTime.Today.ToString("dd/MM/yyyy") + "<BR>Visit date: " +
dateSelectedString + "<BR><BR><BR>Adult tickets: " + numAdult + "<BR>Child tickets: " + numChild + "<BR>Family Passes: " + numFamily +
"<BR>Payment method: " + paymentType + "<BR>Total to pay: $" + totalPrice.ToString("0.00");
}
protected void printButton_Click(object sender, EventArgs e)
{
Response.Clear();
Response.Write(_printString);
Response.Flush();
Response.End();
}
}

When printButton is clicked it is using the value DEFAULT from when the variable is being set.
private string _printString = "DEFAULT";
Is your problem. You need to maintain the state of printString when the variable is modified. Simply assigning _printString to another value is not persisting the change. You could either write a function to assign _printString to the correct value when printButton is clicked, use ViewState or Session or assign _printString in the printButton click function directly as shown below.
protected void printButton_Click(object sender, EventArgs e)
{
_printString = "Harry Potter";
Response.Clear();
Response.Write(_printString);
Response.Flush();
Response.End();
}
Will result in Harry Potter being wrote to the page.
To use Session:
protected void calculateButton_Click(object sender, EventArgs e)
{
_printString = "HARRY POTTER™: THE EXHIBITION Invoice<BR>Today's date: " + DateTime.Today.ToString("dd/MM/yyyy") + "<BR>Visit date: " +
dateSelectedString + "<BR><BR><BR>Adult tickets: " + numAdult + "<BR>Child tickets: " + numChild + "<BR>Family Passes: " + numFamily +
"<BR>Payment method: " + paymentType + "<BR>Total to pay: $" + totalPrice.ToString("0.00");
Session["PrintString"] = _printString;
}
protected void printButton_Click(object sender, EventArgs e)
{
_printString = (string)Session["PrintString"];
Response.Clear();
Response.Write(_printString);
Response.Flush();
Response.End();
}
ViewState:
ViewState["PrintString"] = "HarryPotter";
Then to retrieve the value you can simply do:
_printString = (string)ViewState["PrintString"];
http://msdn.microsoft.com/en-gb/library/ms972976.aspx

All (instance) variables are disposed at the end of the page's lifecycle since HTTP is stateless(even the controls). You could use a ViewState, HiddenField or Session variable instead.
private string PrintString
{
get
{
if (ViewState["PrintString "] == null || string.IsNullOrEmpty((String)ViewState["PrintString"]))
{
ViewState["PrintString"] = "DEFAULT";
}
return ViewState["PrintString"].ToString();
}
set { ViewState["PrintString"] = value; }
}
There are other options:
Nine Options for Managing Persistent User State in Your ASP.NET Application

The button click event is causing a postback and the _printString value is not being persisted. You need to store it in the calculate method via Session or Viewstate and then set it in the print for example: -
protected void calculateButton_Click(object sender, EventArgs e)
{
_printString = "";
_printString = "HARRY POTTER™: THE EXHIBITION Invoice<BR>Today's date: " + DateTime.Today.ToString("dd/MM/yyyy") + "<BR>Visit date: " +
dateSelectedString + "<BR><BR><BR>Adult tickets: " + numAdult + "<BR>Child tickets: " + numChild + "<BR>Family Passes: " + numFamily +
"<BR>Payment method: " + paymentType + "<BR>Total to pay: $" + totalPrice.ToString("0.00");
Session["bigstring"] = _printString;
}
protected void printButton_Click(object sender, EventArgs e)
{
Response.Clear();
_printString = Session["bigstring"].ToString();
Response.Write(_printString);
Response.Flush();
Response.End();
}

Value stored in a variable in an event handler is null later on, why?

In my code I write the value from DropDownList1.SelectedItem.Text to Label1.Text and into uploadFolder in the DropDownList1_SelectedIndexChanged method. When the ASPxUploadControl1_FileUploadComplete method is called, the value is in Label1.Text but not in uploadFolder, which is null. Why is this?
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
if (DropDownList1.SelectedItem != null)
{
Label1.Text = "You selected " + DropDownList1.SelectedItem.Text;
uploadFolder = DropDownList1.SelectedItem.Text;
}
}
protected void ASPxUploadControl1_FileUploadComplete(object sender, DevExpress.Web.ASPxUploadControl.FileUploadCompleteEventArgs e)
{
if (e.IsValid)
{
string uploadDirectory = Server.MapPath("~/files/");
//string uploadDirectory = #"\\DOCSD9F1\TECHDOCS\";
string fileName = e.UploadedFile.FileName;
string path = (uploadDirectory + uploadFolder + "/" + fileName);
//string path = Path.Combine(Path.Combine(uploadDirectory, uploadFolder), fileName);
e.UploadedFile.SaveAs(path);
e.CallbackData = fileName;
}
}

It looks like uploadFolder is a variable you've declared on your page, something like this:
public class MyPage : System.Web.UI.Page
{
string uploadFile = null;
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
// Your code here
}
protected void ASPxUploadControl1_FileUploadComplete(object sender, DevExpress.Web.ASPxUploadControl.FileUploadCompleteEventArgs e)
{
// Your code here
}
}
What's happening is that the content of uploadFile that you're setting in DropDownList1_SelectedIndexChanged isn't being preserved between post-backs, because it isn't a property of one of the controls on the page. You need to store the value somewhere that gets persisted, such as the View State or in Session State.
To do this, you should add to the DropDownList1_SelectedIndexChanged method so it reads something like:
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
if (DropDownList1.SelectedItem != null)
{
Label1.Text = "You selected " + DropDownList1.SelectedItem.Text;
Session["UploadFolder] = DropoDownList1.SelectedItem.Text;
}
}
And adjust the ASPxUploadControl1_FileUploadComplete method so it extracts `uploadFolder from the Session:
string path = (uploadDirectory + Session["UploadFolder"] + "/" + fileName);
If you want to make it look more elegant than that, consider using ViewState in this sort of way:
public string UploadFolder
{
get
{
return (string)ViewState["UploadFolder"];
}
set
{
ViewState["UploadFolder"] = value;
}
}
You can then do this:
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
if (DropDownList1.SelectedItem != null)
{
Label1.Text = "You selected " + DropDownList1.SelectedItem.Text;
UploadFolder = DropoDownList1.SelectedItem.Text;
}
}
And:
string path = (uploadDirectory + UploadFolder + "/" + fileName);

I would imagine that you are not persisting uploadFolder through page post backs. Store the value in a hidden field, e.g.:
<asp:HiddenField ID="hidden_UploadFolder" runat="server" />
And then:
hidden_UploadFolder.Value = DropDownList1.SelectedItem.Text;
You can then read it again on the next post back:
string uploadFolder = hidden_UploadFolder.Value;
Make sure you add error trapping.

It looks like you are setting the value for upload folder in one postback and using it in another. If you want to persist data between postbacks use the Session.
ex.
Session["uploadFolder"] = DropDownList1.SelectedItem.Text;
string path = (uploadDirectory + Session["uploadFolder"].ToString() + "/" + fileName);

Try
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
if (DropDownList1.SelectedItem != null)
{
Label1.Text = "You selected " + DropDownList1.SelectedItem.Text;
Session["uploadFolder"] = DropDownList1.SelectedItem.Text;
}
}
protected void ASPxUploadControl1_FileUploadComplete(object sender, DevExpress.Web.ASPxUploadControl.FileUploadCompleteEventArgs e)
{
if (e.IsValid)
{
string uploadDirectory = Server.MapPath("~/files/");
//string uploadDirectory = #"\\DOCSD9F1\TECHDOCS\";
string fileName = e.UploadedFile.FileName;
string uploadfolder = Session["uploadFolder"] as String;
string path = (uploadDirectory + uploadfolder + "/" + fileName);
//string path = Path.Combine(Path.Combine(uploadDirectory, uploadFolder), fileName);
e.UploadedFile.SaveAs(path);
e.CallbackData = fileName;
}
}