Read Text at a 32-bit Offset from a Remote SFTP File

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Demonstrates the Chilkat SFtp.ReadFileText32 method, which reads up to a number of bytes from a specific 32-bit byte offset of an open handle and decodes them to text. The arguments are the handle, the offset, the maximum number of bytes, and the charset.

Background: Reading from an explicit offset lets you fetch just the part of a file you need — a header, a record at a known position, a slice of a large log — without downloading everything before it. As with offset writes, the offset counts bytes rather than characters, so it must respect the encoded width of any multibyte content.

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bool success = false;

//  Demonstrates the SFtp.ReadFileText32 method, which reads up to a number of bytes from a
//  specific 32-bit byte offset of an open handle and decodes them to text.  The 1st argument is
//  the handle, the 2nd is the offset, the 3rd is the maximum number of bytes, and the 4th is the
//  charset.

Chilkat.SFtp sftp = new Chilkat.SFtp();

//  Connect, authenticate, and initialize the SFTP subsystem.
int port = 22;
success = sftp.Connect("sftp.example.com",port);
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
string password = "mySshPassword";

success = sftp.AuthenticatePw("mySshLogin",password);
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

success = sftp.InitializeSftp();
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

string handle = sftp.OpenFile("subdir/record.dat","readOnly","openExisting");
if (sftp.LastMethodSuccess == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

//  Read 5 bytes starting at byte offset 10, without first reading the bytes before it.
int offset = 10;
int numBytes = 5;
string text = sftp.ReadFileText32(handle,offset,numBytes,"utf-8");
if (sftp.LastMethodSuccess == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

Debug.WriteLine(text);

success = sftp.CloseHandle(handle);
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

sftp.Disconnect();