GetStringFix - method of the PmBuffer object

Reading the text string with fixed length.
String GetStringFix(Long nOffset, Long nLength, [Long nEncoding])
nOffset(Long) Specifies the position of read value in the data block.
The read value must be inside the data block. The item is read either whole or not read at all.
>= 0 - Index (in bytes, zero-based index) in the data block.
-4 - The internal automatic position is used (see the AutoOffset property). It points behind the last read or written value.
This operation shifts the internal automatic position behind the read/written value.
If the items are read/written one by one then it is not necessary to define the position manually, but it is better to use this automated positioning.
nLength(Long) Fixed length in bytes of reserver space in the data block for saved string.
If there is a NULL character inside the fixed length text string then the text string reading is terminated on this spot and therefore is shorter.
If the text string does not contain any NULL character then it is considered to be the while content of defined fixed length.
nEncoding[optional] (Long) Encoding of a text string in the data block.
0 (default) - (ANSI) Each character is stored in a single byte. The values from 0 to 127 represent an ASCII character table that is not changing in meaning. The values from 128 to 255 have different meaning in various localizations (code pages, e.g. Windows 1250).
1 - (UTF-8) Each character is stored in 1, 2 or 4 bytes, it means has variable length. The advantage is that the latin characters (ASCII) are stored in a single byte. Only special characters and characters with diacritics (i.e. national dependent chars) are stored in multiple bytes. This storage is therefore very efficient.
This encoding is commonly used for data exchange, data persistence and on the Web.
2 - (UTF-16) Each character is stored in 2 bytes (or exceptionally in 4 bytes), i.e. it has a fixed length. The advantage is that most characters are stored in 2 bytes so these strings are easy to work with (because of the fixed length).
This encoding is used internally in Windows OS, but also in the JavaScript language or .NET, because the mannipulation with these fixed strings is easier.
CodePage - Each character is stored in one or more bytes according to the specified code page (CodePage). A code page is specified by its number, which is valid across all operating systems and programs. For example 1250 for Windows 1250 or 852 for Latin 2.
This method is also functional in Web panels.
Limitations for Web panels:
nEcoding=0 (ANSI) - encoding does not work for characters with a value greater than 127
nEcoding=1 (UTF-8) - encoding does not work in Internet Explorer.
nEcoding=CodePage - encoding does not work
See also:
JavaScriptSelect and copy to clipboard

var oBuf = Pm.CreatePmBuffer();
var s1 = "Help me!";
oBuf.SetStringFix(-2, s1, 8, 0, 1);

oBuf.AutoOffset = 0;
var nSize = oBuf.GetSize();

var val = oBuf.GetStringFix(-4, nSize, 1);   // val = "Help me!"

Pm9.00.04: Created
PROMOTIC 9.0.25 SCADA system documentation MICROSYS, spol. s r.o.

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