.. highlightlang:: us

.. _mem_compress:

mem_compress
============

.. index:: mem_compress

.. us.tag  mem_compress ENGLISH mem file-zip New420 Changed500

:ref:`mem_compress` compresses a string which may contain 0-characters.

.. function::  ssCompressed = mem_compress(ssString)

.. us.return

**Return Value**

*ssCompressed* is the compressed string. The function inserts an 8 byte long
header at the beginning of the string. The header starts with the 4 characters
``gzc\0`` followed by a 32-Bit value in little endian byte-order (Intel)
which contains the string length of the uncompressed string.

.. us.params

**Parameters**

.. uparam:: ssString

   *ssString* is a scalar string.

.. us.example

**Example**

::

   filename = GetRootDirectory() + "/script/mn_grid.ic";
   fp = fopen(filename, "r");
   s = fread(fp, "char");
   fclose(fp);
   c = mem_compress(s);
   print "Size uncompressed:", strlen(s);
   print "Size compressed:", mem_len(c);

Output:

::

   Size uncompressed:
   91099.0000 
   Size compressed:
   17992.0000 

.. us.comment

**Comment**

This function uses the zlib-Library
(http://www.gzip.org/zlib/).
Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler.

UniPlot verwendet Unicode-Strings, die zwei Bytes pro Zeichen verwenden (UTF-16).
Die Funktion :ref:`mem_compress` verwendet nur jeweils die unteren Bytes des
Unicode-Strings.

Müssen alle Bytes des Unicode-Strings komprimiert werden, können die Funktionen
:ref:`mem_unpack` und :ref:`mem_pack` vor dem Komprimieren bzw. nach dem
Dekomprimieren verwendet werden:

.. highlight:: none

::

   * mc = mem_compress(mem_unpack("你们好"))
   * print mem_pack(mem_uncompress(mc))
   你们好

.. highlight:: us

.. us.history

**History**

.. list-table::
   :header-rows: 1

   * - Version
     - Description
   * - 5.0.0
     - Unicode strings.
   * - 4.2.0
     - New

.. seealso::
   :ref:`overview-strings`,
   :ref:`file-zip`,
   :ref:`mem_uncompress`,
   :ref:`CompressFile`,
   :ref:`DeCompressFile`,
   :ref:`mem_pack`,
   :ref:`mem_unpack`

:sub:`id-1359285`