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POAccessing a vector which is a value in a map to run the equality operator on it with another vector
 

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  1. POAccessing a vector which is a value in a map to run the equality operator on it with another vector
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    <p>I have a vector that is made up of maps which have the following type definition:</p> <p><code>std::map&lt; int, std::vector&lt;int&gt; &gt;</code></p> <p>Thus, the definition of the vector itself is: </p> <p><code>std::vector&lt; std::map&lt; int, std::vector&lt;int&gt; &gt; &gt;</code></p> <p>Now I am creating a vector of integers and inserting it in a map with an integer key and adding the map itself to the outer vector:</p> <pre><code> std::map&lt;int, std::vector&lt;int&gt; &gt; vDescriptorAtom; vDescriptorAtom.insert( std::make_pair(498, vListOfIds) ); messageDescriptorVector.push_back( vDescriptorAtom ); </code></pre> <p>Where vListOfIds itself is a vector of integers. </p> <p>At a later stage I want to extract the inner vector and compare with another vector that I possess. I was under the impression that I can easily use the <code>==</code> operator between the two vectors to do the comparison. But I am having some trouble doing this. </p> <p>I tried:</p> <pre><code> for ( int i = 0 ; i &lt;= messageDescriptorVector.size(); i++ ) { if ( current_tag_stack == (messageDescriptorVector.at(i))-&gt;second ) { vFoundMatchingDescriptor = true; break; } } </code></pre> <p>Note that current_tag_stack has the following definition: </p> <pre><code>std::vector&lt;int&gt; current_tag_stack; </code></pre> <p>But I am getting this error: </p> <pre><code>base operand of â-&gt;â has non-pointer type âstd::map&lt;int, std::vector&lt;int, std::allocator&lt;int&gt; &gt;, std::less&lt;int&gt;, std::allocator&lt;std::pair&lt;const int, std::vector&lt;int, std::allocator&lt;int&gt; &gt; &gt; &gt; &gt;â </code></pre> <p>What am I doing wrong ? </p> <p><strong>EDIT</strong></p> <p>As suggested by a comment, I tried to access the vector that I have stored inside the map as: <code>messageDescriptorVector.at(i).second</code> but it is giving me this error: <code>âclass std::map&lt;int, std::vector&lt;int, std::allocator&lt;int&gt; &gt;, std::less&lt;int&gt;, std::allocator&lt;std::pair&lt;const int, std::vector&lt;int, std::allocator&lt;int&gt; &gt; &gt; &gt; &gt;â has no member named âsecondâ </code></p>
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    1. USChani
    1. USChani
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      1. VTUpMod
    1. COThe error message is pretty clear on that. Use `.`, not `->`.
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      1. USKerrek SB
    2. CO@KerrekSB Nope, that did not work. It just threw this error: ` âclass std::map<int, std::vector<int, std::allocator<int> >, std::less<int>, std::allocator<std::pair<const int, std::vector<int, std::allocator<int> > > > >â has no member named âsecondâ `
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      1. USChani
    3. COFor God's sake use typedefs
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      1. USSlava
 

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