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String constructors [C++ Reference]
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<h2><a name="string_constructors" id="string_constructors">String constructors</a></h2>
<div class="level2">
<p>
Syntax:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="co2">#include <string></span>
<span class="kw4">string</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span><span class="br0">(</span> <span class="kw4">const</span> string<span class="sy0">&</span> s <span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span><span class="br0">(</span> size_type length<span class="sy0">,</span> Char ch <span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span><span class="br0">(</span> <span class="kw4">const</span> Char<span class="sy0">*</span> str <span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span><span class="br0">(</span> <span class="kw4">const</span> Char<span class="sy0">*</span> str<span class="sy0">,</span> size_type length <span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span><span class="br0">(</span> <span class="kw4">const</span> string<span class="sy0">&</span> str<span class="sy0">,</span> size_type index<span class="sy0">,</span> size_type length <span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span><span class="br0">(</span> input_iterator start<span class="sy0">,</span> input_iterator end <span class="br0">)</span><span class="sy0">;</span>
~<span class="kw4">string</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span></pre>
<p>
The string constructors create a new string containing:
</p>
<ul>
<li class="level1"><div class="li"> nothing; an empty string,</div>
</li>
<li class="level1"><div class="li"> a copy of the given string s,</div>
</li>
<li class="level1"><div class="li"> length copies of ch,</div>
</li>
<li class="level1"><div class="li"> a duplicate of str (optionally up to length characters long),</div>
</li>
<li class="level1"><div class="li"> a substring of str starting at index and length characters long</div>
</li>
<li class="level1"><div class="li"> a string of characters denoted by the start and end iterators</div>
</li>
</ul>
<p>
For example,
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="kw4">string</span> str1<span class="br0">(</span> <span class="nu0">5</span><span class="sy0">,</span> <span class="st0">'c'</span> <span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span> str2<span class="br0">(</span> <span class="st0">"Now is the time..."</span> <span class="br0">)</span><span class="sy0">;</span>
<span class="kw4">string</span> str3<span class="br0">(</span> str2<span class="sy0">,</span> 11<span class="sy0">,</span> 4 <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> str1 <span class="sy0"><<</span> endl<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> str2 <span class="sy0"><<</span> endl<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> str3 <span class="sy0"><<</span> endl<span class="sy0">;</span></pre>
<p>
displays
</p>
<pre class="c code c++" style="font-family:monospace;"> ccccc
Now is the time...
<span class="me1">time</span></pre>
<p>
The string constructors usually run in <a href="../complexity.html" class="wikilink1" title="complexity">linear time</a>, except the empty
constructor, which runs in <a href="../complexity.html" class="wikilink1" title="complexity">constant time</a>.
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