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POMemory corrupt in adding string to vector<string> loop
 

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  1. POMemory corrupt in adding string to vector<string> loop
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    <p>This is on Visual Studio 2008 on a dual-core, 32 bit Vista machine. In the debug code this runs fine, but in Release mode this bombs:</p> <pre><code>void getFromDB(vector&lt;string&gt;&amp; dates) { ... sql::Resultset res = stmt-&gt;executeQuery("SELECT FROM ..."); while (res-&gt;next()) { string date = res-&gt;getString("date"); dates.push_back(date); } // &lt;&lt;&lt; crashing here (line 56) delete res; } </code></pre> <p>The MySQL C++ connector has this method in it's ResultSet:</p> <pre><code>virtual std::string getString(const std::string&amp; columnLabel) const = 0; </code></pre> <p>For some reason in the release compiled (against a MySQL C++ connector DLL) this crashes at the end of the loop with a heap corruption:</p> <blockquote> <p>HEAP[sa-ms-release.exe]: Invalid address specified to RtlFreeHeap( 024E0000, 001C4280 ) Windows has triggered a breakpoint in sa-ms-release.exe.</p> </blockquote> <pre><code> ntdll.dll!_RtlpBreakPointHeap@4() + 0x28 bytes ntdll.dll!_RtlpValidateHeapEntry@12() + 0x713e8 bytes ntdll.dll!_RtlDebugFreeHeap@12() + 0x9a bytes ntdll.dll!@RtlpFreeHeap@16() + 0x145cf bytes ntdll.dll!_RtlFreeHeap@12() + 0xed5 bytes kernel32.dll!_HeapFree@12() + 0x14 bytes &gt; sa-ms-release.exe!free(void * pBlock=0x001c4280) Line 110 C sa-ms-release.exe!std::allocator&lt;char&gt;::deallocate(char * _Ptr=0x001c4280, unsigned int __formal=32) Line 140 + 0x9 bytes C++ sa-ms-release.exe!std::basic_string&lt;char,std::char_traits&lt;char&gt;,std::allocator&lt;char&gt; &gt;::_Tidy(bool _Built=true, unsigned int _Newsize=0) Line 2158 C++ sa-ms-release.exe!std::basic_string&lt;char,std::char_traits&lt;char&gt;,std::allocator&lt;char&gt; &gt;::~basic_string&lt;char,std::char_traits&lt;char&gt;,std::allocator&lt;char&gt; &gt;() Line 907 C++ sa-ms-release.exe!StyleData:: getFromDB( std::vector&lt;std::basic_string&lt;char,std::char_traits&lt;char&gt;,std::allocator&lt;char&gt; &gt;,std::allocator&lt;std::basic_string&lt;char,std::char_traits&lt;char&gt;,std::allocator&lt;char&gt; &gt; &gt; &gt; &amp; dates) Line 56 + 0x69 bytes C++ </code></pre> <p>I think I may be violating some basic C++ rule that causes the destructor to be called on a string I want to preserve inside the vector.</p> <p>If I replace</p> <pre><code>string date = res-&gt;getString("date") </code></pre> <p>with </p> <pre><code>string date = string ("2008-11-23"); </code></pre> <p>everything works fine. It seems to have to do with the string returned from the MySQL C++ Connector getString() method. The returned string is destroyed and that causes the problem, I guess. But more likely something else is wrong. I am using the release (opt) MySQL connector.</p>
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    1. USMartin Stein
    1. USMartin Stein
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      1. VTUpMod
    1. COWhich STL version, SDK or VS you are compiling against??
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      1. USvpram86
    2. COPoviding line numbers in your code might help (the last line in message above specifies line 56 in StyleData::getFromDB). Disassebly might help even more...
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      1. USTomek
    3. COwhat is the signature of sql::Resultset::getString(...);?
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      1. USFrank Bollack
 

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