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POSegmentation Fault - vector string - multimap implementation
 

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  1. POSegmentation Fault - vector string - multimap implementation
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    <p>I try to make this implementation of a multimap in C++, but I run into a seg fault when trying to access the vector "values", even though values.size() returns the correct answer.</p> <p>I know the seg fault happens on line 22, but I don't know why. Would appreciate any help.</p> <pre><code>#include &lt;iostream&gt; #include &lt;vector&gt; #include &lt;string.h&gt; using namespace std; template&lt;class DT1,class DT2&gt; class Pair { public: Pair(DT1 key_in, DT2 value_in) { key = key_in; values.push_back(value_in); } DT1 key; vector&lt;DT2&gt; values; int insert_value(DT2 item) { bool value_found = false; cout &lt;&lt; "values size "&lt;&lt;values.size() &lt;&lt; endl; cout &lt;&lt; "test " &lt;&lt; values[0] &lt;&lt; endl; for (unsigned int i = 0; i &lt; values.size(); i++) { cout &lt;&lt;"i " &lt;&lt; i &lt;&lt; endl; if (values[i] == item) value_found = true; } if (value_found == false) { cout&lt;&lt;"not found"&lt;&lt;endl; values.push_back(item); } return 0; } }; template&lt;class T1, class T2&gt; class MultiMap { public: MultiMap() {}; vector&lt;Pair&lt;T1, T2&gt; &gt; pair_container; int insert(T1 key_in, T2 value_in) { bool key_found = false; unsigned int i; for (i = 0; i &lt; pair_container.size(); i++) { if (pair_container[i].key == key_in) key_found = true; } if (key_found == false) pair_container.push_back(Pair&lt;T1,T2&gt;(key_in, value_in)); if (key_found == true) { pair_container[i].insert_value(value_in); // seg fault } return 0; } }; int main() { MultiMap&lt;char, string&gt; Map1; Map1.insert('a', "anchor"); cout &lt;&lt; Map1.pair_container[0].values[0] &lt;&lt; endl; Map1.insert('a', "application"); // seg fault cout &lt;&lt; "hello!"&lt;&lt;endl; Map1.insert('b', "boolean"); return 0; } </code></pre>
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    1. USTri Nguyen
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    1. COWhere is line 22?
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    2. COSorry I just realized there's no line numbering here. It's where this line appears: cout << "test " << values[0] << endl;
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