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String Stream Constructors [C++ Reference]
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<h2><a name="string_stream_constructors" id="string_stream_constructors">String Stream Constructors</a></h2>
<div class="level2">
<p>
Syntax:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="co2">#include <sstream></span>
stringstream<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span>
explicit stringstream<span class="br0">(</span> ios_base<span class="sy0">::</span><span class="me2">openmode</span> mode <span class="br0">)</span><span class="sy0">;</span>
stringstream<span class="br0">(</span> <span class="kw4">const</span> string<span class="sy0">&</span> s<span class="sy0">,</span> ios_base<span class="sy0">::</span><span class="me2">openmode</span> mode <span class="br0">)</span><span class="sy0">;</span>
ostringstream<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span>
explicit ostringstream<span class="br0">(</span> ios_base<span class="sy0">::</span><span class="me2">openmode</span> mode <span class="br0">)</span><span class="sy0">;</span>
ostringstream<span class="br0">(</span> <span class="kw4">const</span> string<span class="sy0">&</span> s<span class="sy0">,</span> ios_base<span class="sy0">::</span><span class="me2">openmode</span> mode <span class="br0">)</span><span class="sy0">;</span>
istringstream<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span>
explicit istringstream<span class="br0">(</span> ios_base<span class="sy0">::</span><span class="me2">openmode</span> mode <span class="br0">)</span><span class="sy0">;</span>
istringstream<span class="br0">(</span> <span class="kw4">const</span> string<span class="sy0">&</span> s<span class="sy0">,</span> ios_base<span class="sy0">::</span><span class="me2">openmode</span> mode <span class="br0">)</span><span class="sy0">;</span></pre>
<p>
The stringstream, ostringstream, and istringstream objects are used for input
and output to a string. They behave in a manner similar to fstream, ofstream
and ifstream objects.
</p>
<p>
The optional <code>mode</code> parameter defines how the file is to be opened, according to
the <a href="../../io/io_flags#mode_flags.html" class="wikilink1" title="io:io_flags">IO stream mode flags</a>.
</p>
<p>
An ostringstream object can be used to write to a string. This is similar to
the Standard C Library <a href="../../c/io/sprintf.html" class="wikilink1" title="c:io:sprintf">sprintf</a> function. For example:
</p>
<pre class="c code c++" style="font-family:monospace;"> ostringstream s1<span class="sy0">;</span>
<span class="kw4">int</span> i <span class="sy0">=</span> <span class="nu0">22</span><span class="sy0">;</span>
s1 <span class="sy0"><<</span> <span class="st0">"Hello "</span> <span class="sy0"><<</span> i <span class="sy0"><<</span> endl<span class="sy0">;</span>
<span class="kw4">string</span> s2 <span class="sy0">=</span> s1.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span>
<a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0"><<</span> s2<span class="sy0">;</span></pre>
<p>
An istringstream object can be used to read from a string. This is similar to
the Standard C Library <a href="../../c/io/sscanf.html" class="wikilink1" title="c:io:sscanf">sscanf</a> function. For example:
</p>
<pre class="c code c++" style="font-family:monospace;"> istringstream stream1<span class="sy0">;</span>
<span class="kw4">string</span> string1 <span class="sy0">=</span> <span class="st0">"25"</span><span class="sy0">;</span>
stream1.<span class="me1">str</span><span class="br0">(</span>string1<span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">int</span> i<span class="sy0">;</span>
stream1 <span class="sy0">>></span> i<span class="sy0">;</span>
<a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0"><<</span> i <span class="sy0"><<</span> endl<span class="sy0">;</span> <span class="co1">// displays 25</span></pre>
<p>
You can also specify the input string in the istringstream constructor as in
this example:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="kw4">string</span> string1 <span class="sy0">=</span> <span class="st0">"25"</span><span class="sy0">;</span>
istringstream stream1<span class="br0">(</span>string1<span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">int</span> i<span class="sy0">;</span>
stream1 <span class="sy0">>></span> i<span class="sy0">;</span>
<a href="http://www.opengroup.org/onlinepubs/009695399/functions/cout.html"><span class="kw3">cout</span></a> <span class="sy0"><<</span> i <span class="sy0"><<</span> endl<span class="sy0">;</span> <span class="co1">// displays 25</span></pre>
<p>
A stringstream object can be used for both input and output to a string like an
fstream object.
</p>
<p>
Related Topics: <a href="../../io/start.html" class="wikilink1" title="io:start">C++ I/O streams</a>
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