C#

Member 14506843 wrote:

Can anyone please help me?

if (File.Exists(path1))
{
    File.Delete(path1);
}

try
{
    using (Stream stream1 = new FileStream(path1, FileMode.Open, FileAccess.Read))
    {
        stream1.Position = 0L;
        TheData1 = (Data1) dcs1.ReadObject(stream1);
    }
}
catch (Exception ex)
{
    MessageBox.Show($"{path1} cannot be read");
    return;
}

BillWoodruff wrote:

And, if the file does not exist, I do want it to be created.

[DataContract]
public class Data1
{
    public Data1(string id)
    {
        ID = id;
    }

    [DataMember]
    public string ID { set; get; }
}

BillWoodruff wrote:

And, if the file does not exist, I do want it to be created.

OpenOrCreate

If the file doesn't exist, create it.

If it does exist, do not truncate it.

Create

If the file doesn't exist, create it.

If it does exists, truncate it.

Quote:

OpenOrCreate Specifies that the operating system should open a file if it exists; otherwise, a new file should be created. If the file is opened with FileAccess.Read, FileIOPermissionAccess.Read permission is required. If the file access isFileAccess.Write, FileIOPermissionAccess.Write permission is required. If the file is opened withFileAccess.ReadWrite, both FileIOPermissionAccess.Read and FileIOPermissionAccess.Write permissions are required.

using (var s = File.Open(path, FileMode.OpenOrCreate))
using (var w = new StreamWriter(s))
{
    w.Write("0123456789");
    w.Flush();
}

// File now contains: 0123456789

using (var s = File.Open(path, FileMode.OpenOrCreate))
using (var w = new StreamWriter(s))
{
    w.Write("ABC");
    w.Flush();
}

// File now contains: ABC3456789

BillWoodruff wrote:

however, that MsDN docs don't mention it ... sadly ... is not a surprise.

Quote:

Specifies that the operating system should open a file if it exists; otherwise, a new file should be created.

Richard MacCutchan wrote:

The documentation is quite clear

using (Stream stream1 = new FileStream(path1, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None))
{
    dcs1.WriteObject(stream1, this.TheData1);
    stream1.Position = 0L; // as if this would help
    stream1.Close(); // throwing salt over shoulder
}

using (Stream stream1 = new FileStream(path1, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None))
{
    stream1.Position = 0L;
    dcs1.WriteObject(stream1, this.TheData1);
    stream1.Close(); // throwing salt over shoulder
}