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<p><a href="../index.html"><img src="title-21.png" width="253" height="39" alt="C++ Portable Types Library (PTypes) Version 2.1" border="0"></a>
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<p class="hpath"><a href="index.html">Top</a>: <a href="basic.html">Basic types</a>:
string</p>
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<h5><a href="string.constructors.html">Constructors/destructors</a></h5>
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<h5><a href="string.operators.html">Operators</a></h5>
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<h5><a href="string.typecasts.html">Typecasts</a></h5>
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<h5><a href="string.manipulation.html">Manipulation</a></h5>
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<h5><a href="string.conversion.html">Conversion</a></h5>
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<p>The <span class="lang">string</span> class implements dynamically allocated
reference-counted 8-bit character strings. The <span class="lang">string</span>
class is a mixture of L-type and null-terminated strings: it has both the length
indicator and the terminating null-symbol. The length of a string is theoretically
limited to <span class="lang">INT_MAX</span>, and practically is limited to the
amount of virtual memory space available to the application. </p>
<p>A string object itself contains only a reference to the first character of
the string buffer. A string object can be implicitly converted to a null-terminated
string, either a variable or passed as an actual parameter, thus allowing to combine
both PTypes strings and traditional C strings in your application. A string object
converted to <span class="lang">char*</span> or <span class="lang">const char*</span>
never returns <span class="lang">NULL</span> pointers: it guarantees to always
point to some data, even if the string is zero-sized.</p>
<p>The reference counting mechanism works <b>transparently</b> (known also as
copy-on-write) and <b>safely</b> with regard to multithreading. You can manipulate
string objects as if each object had its own copy of string data. Whenever you
modify a string object the library safely detaches the buffer from all other string
objects that may be using the same buffer and creates a unique copy so that changes
won't affect the other "holders" of this string.</p>
<p><b>NOTE on multithreading</b>: the dynamic string objects themselves are NOT
thread-safe. In other words, each thread can manipulate objects (variables) of
type <span class="lang">string</span> only within their scope. However, it is
safe to pass strings as (copy) parameters when, for example, sending a message
to a concurrent thread through a message queue. Whenever the recipient thread
tries to modify the string, the shared data buffer is safely detached.</p>
<p>The string class is declared in <a href="include/ptypes.h.html"><ptypes.h></a>.</p>
<p class="seealso">See also: <a href="string.constructors.html">Constructors/destructors</a>,
<a href="string.operators.html">Operators</a>, <a href="string.typecasts.html">Typecasts</a>,
<a href="string.manipulation.html">Manipulation</a>, <a href="string.conversion.html">Conversion</a></p>
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