Issues append data to a .csv File using C#

Question

I am manipulating a csv file using C# but I have an issue. When I added a new row, the first iteration does successful, but the second one overwrite the same row previous.

Example CSV File:

Name, LastName, Age

David, Todd, 28

Juan, Perez, 30

First iteration:

Name, LastName, Age

David, Todd, 28

Juan, Perez, 30

Pepe, Hernandez, 32

Second iteration:

Name, LastName, Age

David, Todd, 28

Juan, Perez, 30

Pepe, Hernandez, 32Maria,Lopez,35

What am I doing wrong?

This is my code:

string newFileName = "C:\\names.csv";
string nameDetails = txtName.Text + "," + txtLastName.Text + "," + txtAge.Text;
if (!File.Exists(newFileName))
{

    string nameHeader = "Name" + "," + 
    "LastName" + "," + "Age" + Environment.NewLine;

    File.WriteAllText(newFileName, nameHeader);

}    

File.AppendAllText(newFileName, nameDetails);

Thanks!

File.WriteAllText overwrites your file each time, use AppendAllText instead. Write the header in first case if !Exists — CRice
– CRice, Commented Sep 14, 2016 at 4:22
@CRice writealltext is only called if the file does not exist — Baahubali
– Baahubali, Commented Sep 14, 2016 at 4:45

The Shooter · Accepted Answer · 2016-09-14 05:25:32Z

1

You are missing

+ Environment.NewLine

while calling

File.AppendAllText

It should be there as well i.e. it should be

File.AppendAllText(newFileName, nameDetails + Environment.NewLine);

answered Sep 14, 2016 at 5:25

The Shooter

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1 Comment

David Tod Over a year ago

Thanks The shooter, simplest solution! :)

Soma Mbadiwe · Accepted Answer · 2016-09-14 04:44:47Z

Just change your code to the following:

string newFileName = "C:\\names.csv";
string nameDetails = txtName.Text + "," + txtLastName.Text + "," + txtAge.Text;
if (!File.Exists(newFileName))
{
    string nameHeader = "Name,LastName,Age\n"; //No point concatenating
    nameDetails = nameHeader + nameDetails;
}
File.AppendAllText(newFileName, nameDetails);

Side Note: You can keep things a bit more tidy by using string.Format. If you do, your code will become something like this:

string newFileName = "C:\\names.csv";
string nameDetails = string.Format("{0},{1},{2}\n", txtName.Text, txtLastName.Text, txtAge.Text);
if (!File.Exists(newFileName))
{
    nameDetails = "Name,LastName,Age\n" + nameDetails;
}
File.AppendAllText(newFileName, nameDetails);

And if you're using the latest c# 6, things can be made even nicer:

string newFileName = "C:\\names.csv";
string nameDetails = $"{txtName.Text},{txtLastName.Text},{txtAge.Text}\n");
if (!File.Exists(newFileName))
{
    nameDetails = "Name,LastName,Age\n" + nameDetails;
}
File.AppendAllText(newFileName, nameDetails);

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