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POunable to push items in vector and list in C++?
 

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    <p>This is a basic merge sort program:</p> <p>The problem is when I try to push item in to "vector merged", nothing happens. (Please refer the gdb data below the code)</p> <pre><code>vector&lt;long&gt; merge(vector&lt;long&gt; &amp;L, vector&lt;long&gt; &amp;R){ int i = 0; int j = 0; vector&lt;long&gt; merged; while((i &lt; L.size())&amp;&amp;(j &lt; R.size())){ if ((L[i] &lt;= R[j])){ merged.push_back(L[i]); i++; }else{ merged.push_back(R[j]); j++; } while(i &lt; L.size()) { merged.push_back(L[i]); i++; } while(j &lt; R.size()) { merged.push_back(R[j]); j++; } return merged; } } </code></pre> <p>//===================================GDB DATA===================================</p> <pre><code>(gdb) n 52 int i = 0; (gdb) 53 int j = 0; (gdb) 54 vector&lt;long&gt; merged; (gdb) print i $2 = 0 (gdb) print merged $3 = {&lt;std::_Vector_base&lt;long, std::allocator&lt;long&gt; &gt;&gt; = { _M_impl = {&lt;std::allocator&lt;long&gt;&gt; = {&lt;__gnu_cxx::new_allocator&lt;long&gt;&gt; = {&lt;No data fields&gt;}, &lt;No data fields&gt;}, _M_start = 0x7fffffffdcd0, _M_finish = 0x7fffffffdcf0, _M_end_of_storage = 0x7fffffffdde0}}, &lt;No data fields&gt;} (gdb) print *(merged._M_impl._M_start)@merged.size() $4 = {140737488346528, 4199556, 140737488346432, 140737488346656} Problem I: Why the merged vector is not null? Or did I used wrong gdb command?? But same command works on other vectors in this program.. (gdb) $5 = {140737488346528, 4199556, 140737488346432, 140737488346656} (gdb) n 56 while((i &lt; L.size())&amp;&amp;(j &lt; R.size())){ (gdb) print *(merged._M_impl._M_start)@merged.size() $6 = {140737488346528, 4199556, 140737488346432, 140737488346656} (gdb) n 57 if ((L[i] &lt;= R[j])){ (gdb) print L[i] $7 = (long &amp;) @0x6060b0: 31616136 (gdb) print R[i] $8 = (long &amp;) @0x6060d0: 1873051691 (gdb) n 58 merged.push_back(L[i]); (gdb) print *(merged._M_impl._M_start)@6 $14 = {140737488346528, 4199556, 140737488346432, 140737488346656, 6316272, 6316280} // Before any push_back operation, dump the content of merged. (gdb) n 59 i++; // Question 2, Push_back does not work... (gdb) print *(merged._M_impl._M_start)@1 $17 = {140737488346528} (gdb) print *(merged._M_impl._M_start)@2 $18 = {140737488346528, 4199556} (gdb) print *(merged._M_impl._M_start)@8 $19 = {140737488346528, 4199556, 140737488346432, 140737488346656, 6316272, 6316280, 6316280, 4205125} </code></pre> <p>Could anyone give me a hand??</p>
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