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    <p>A vector is size 0 until you tell it to resize, or unless you initialize it with a specific size. Pass the size of your vector in when you create it:</p> <pre><code>for(int i=1;i&lt;112;i++){ n_2.push_back(vector&lt;struct nodo&gt;(112-i)); for(int j=1;j&lt;112-i;j++){ n_2[i][j].last_prod=j; } } </code></pre> <p>Also, it looks like you are skipping over the 0th index, which means your first value in your array will be skipped. That is probably undesired. </p> <p>Finally, if your array is a constant size, consider using <a href="http://en.cppreference.com/w/cpp/container/array" rel="nofollow">std::array</a> rather than std::vector. Note that std::array is a C++11 feature and may not be available depending on your compiler.</p> <p>If I were writing this code, I'd probably write it like this:</p> <pre><code>#include &lt;array&gt; using namespace std; // allocate an array of 112 &lt;struct nodo&gt; arrays, each of size 112 array&lt;array&lt;struct nodo, 112&gt;, 112&gt; n_2; for (int i = 0; i &lt; 112; i++) { for (int j = 0; j &lt; 112; j++) { n_2[i][j].last_prod = j; } } </code></pre> <p>Or alternatively, if I don't have a compiler that supports C++11:</p> <pre><code>#include &lt;vector&gt; using namespace std; // allocate a vector of size 112 of &lt;struct nodo&gt; vectors, each of size 112 vector&lt;vector&lt;struct nodo&gt; &gt; n_2(112, vector&lt;struct nodo&gt;(112)); for (int i = 0; i &lt; 112; i++) { for (int j = 0; j &lt; 112; j++) { n_2[i][j].last_prod = j; } } </code></pre> <p>Even more ideally, you should use a 1 dimensional vector, and simply treat it as a 2 dimensional vector. This way, you can do a single allocation of memory all at once rather than 112 smaller allocations. This is getting pretty nitpicky but obviously a O(1) solution is better than an O(n) solution which is better than a O(n^2) solution in terms of allocations since allocations are slow.</p>
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    1. POhandling a 2 dimensional vector c++
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    1. USAndrew Rasmussen
    1. USAndrew Rasmussen
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    1. COskipping the 0th index is done on purpose for the sake of simplicity in reading solutions. but there's still some problem left, as it doesn't work
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      1. USMarcoBi
    2. COOh how I wish I could downvote comments... "skipping the 0th index is done on purpose for the sake of simplicity in reading solutions"--bad idea. It is much better to actually learn how the language works than to attempt to force it to work "intuitively". If you try to do it this way then you have to do other odd things such as creating vectors one larger than you need. You will simply have to create a new abstraction on top of the existing framework, and this will trip you up eventually.
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    3. COIt may be simple in terms of you being able to read it, but simple in terms of every other C programmer in the world it will not be.</yoda> My code should work, if you're still running into issues, it has nothing to do with the code in your question.
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