有关map的输入 c++

已经有
<br>typedef pair &lt;int, int&gt; Map_Int_Pair;
<br>
<br>   m1.insert ( Map_Int_Pair ( 1, 10 ) );
<br>   m1.insert ( Map_Int_Pair ( 2, 20 ) );
<br>   m1.insert ( Map_Int_Pair ( 3, 30 ) );
<br>再加
<br>// Using pair as a return type for a function
<br>   pair&lt; map&lt;int,int&gt;::iterator, bool &gt; pr1, pr2;
<br>   pr1 = m1.insert ( Map_Int_Pair ( 4, 40 ) );
<br>   pr2 = m1.insert ( Map_Int_Pair (1, 10 ) );
<br>运行
<br> if( pr1.second == true )
<br>   {
<br>      cout &lt;&lt; "The element (4,40) was inserted successfully in m1."
<br>           &lt;&lt; endl;
<br>   }
<br>   else   
<br>   {
<br>      cout &lt;&lt; "The element with a key value ofn"
<br>           &lt;&lt; " ( (pr1.first) -&gt; first ) = " &lt;&lt; ( pr1.first ) -&gt; first
<br>           &lt;&lt; " is already in m1,n so the insertion failed." &lt;&lt; endl;
<br>   }
<br>
<br>   if( pr2.second == true )
<br>   {
<br>      cout &lt;&lt; "The element (1,10) was inserted successfully in m1."
<br>           &lt;&lt; endl;
<br>   }
<br>   else   
<br>   {
<br>      cout &lt;&lt; "The element with a key value ofn"
<br>           &lt;&lt; " ( (pr2.first) -&gt; first ) = " &lt;&lt; ( pr2.first ) -&gt; first
<br>           &lt;&lt; " is already in m1,n so the insertion failed." &lt;&lt; endl;
<br>   }
<br>}
<br>
<br>结果：
<br>The element (4,40) was inserted successfully in m1.
<br>The element with a key value of
<br> ( (pr2.first) -&gt; first ) = 1 is already in m1,
<br> so the insertion failed.
<br>
<br>我想问的是已经有的就不能再重复往里输了吗？

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