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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head> <meta name="generator" content= "HTML Tidy for Linux/x86 (vers 1 September 2005), see www.w3.org"> <title>insert</title> <link href="../cppreference.css" rel="stylesheet" type="text/css"></head><body><table> <tr> <td> <div class="body-content"> <div class="header-box"> <a href="../index.html">cppreference.com</a> > <a href= "index.html">C++ Maps</a> > <a href="insert.html">insert</a> </div> <div class="name-format"> insert </div> <div class="syntax-name-format"> Syntax: </div> <pre class="syntax-box"> #include <map> iterator insert( iterator i, const <a href="../containers.html">TYPE</a>& pair ); void insert( <a href="../iterators.html">input_iterator</a> start, <a href="../iterators.html">input_iterator</a> end ); pair<iterator,bool> insert( const <a href="../containers.html">TYPE</a>& pair );</pre> <p>The function insert() either:</p> <ul> <li>inserts <em>pair</em> after the element at <em>pos</em> (where <em>pos</em> is really just a suggestion as to where <em>pair</em> should go, since sets and maps are ordered), and returns an iterator to that element.</li> <li>inserts a range of elements from <em>start</em> to <em>end</em>.</li> <li>inserts <em>pair</em><<em>key</em>,<em>val</em>>, but only if no element with key <em>key</em> already exists. The return value is an iterator to the element inserted (or an existing pair with key <em>key</em>), and a boolean which is true if an insertion took place.</li> </ul> <p>For example, the following code uses the insert() function (along with the make_pair() function) to insert some data into a map and then displays that data:</p> <pre class="example-code"> map<string,int> theMap; theMap.insert( make_pair( "Key 1", -1 ) ); theMap.insert( make_pair( "Another key!", 32 ) ); theMap.insert( make_pair( "Key the Three", 66667 ) ); map<string,int>::iterator iter; for( iter = theMap.begin(); iter != theMap.end(); ++iter ) { cout << "Key: '" << iter->first << "', Value: " << iter->second << endl; }</pre> <p>When run, the above code displays this output:</p> <pre class="example-code"> Key: 'Another key!', Value: 32 Key: 'Key 1', Value: -1 Key: 'Key the Three', Value: 66667</pre> <p>Note that because maps are sorted containers, the output is sorted by the key value. In this case, since the map key data type is <a href="../cppstring/index.html">string</a>, the map is sorted alphabetically by key.</p> <div class="related-name-format"> Related topics: </div> <div class="related-content"> <a href="map_operators.html">Map operators</a> </div> </div> </td> </tr> </table></body></html>⌨️ 快捷键说明
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