(.NET Core C#) File Existence Check

Testing to see if a file exists on the FTP server. The GetSizeByName method is a convenient way to check if a file exists. It will return -1 if the file does not exist, otherwise it returns the size of the file in bytes.

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Ftp2 ftp = new Chilkat.Ftp2();

ftp.Hostname = "ftp.example.com";
ftp.Username = "username";
ftp.Password = "password";

// Connect and login to the FTP server.
bool success = ftp.Connect();
if (success != true) {
    Debug.WriteLine(ftp.LastErrorText);
    return;
}

// Set the current remote directory to where the file is located:
success = ftp.ChangeRemoteDir("something");
if (success != true) {
    Debug.WriteLine(ftp.LastErrorText);
    return;
}

// Test to see if the file exists by getting the file size by name. 
// If a -1 is returned, the file does not exist.
int fileSize = ftp.GetSizeByName("test123.txt");
if (fileSize < 0) {
    Debug.WriteLine("file does not exist");
}
else {
    Debug.WriteLine("file exists and is " + Convert.ToString(fileSize) + " bytes in size");
}

success = ftp.Disconnect();