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Editorial Team
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Asked: 2026-06-01T15:38:27+00:00

I get an exception while executing following piece of code bool FieldValueMessage::Get(const std::string &field,

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I get an exception while executing following piece of code

bool FieldValueMessage::Get(const std::string &field, double & value)
{
    string text;
    if(Get(field,text))
    {
        std::stringstream sstr(text);
        sstr >> value;
        if(sstr.fail())
            return false;
        else
            return true;
    } 
    else 
    {
        return false;
    }        
}

Get function is as below

bool HashMapMessage::Get(const std::string &field, std::string & value)
{
    Field2Value::iterator i = f2v.find(field);
    if(i==f2v.end()){
        return false;
    } else {
        value = i->second;
        return true;
    }
}

caller of Get function. I don’t see any issue here.

for(i=quote_fields.begin(),j=0;i!=quote_fields.end();i++,j++){
    if (msg->Get((*i).c_str(),tmp)){
        if(tmp>0 && x->staging_data[j+1]!=tmp){
            x->staging_data[j+1] = tmp;
            has_update = true;
        }
    }
}

Call Stack is 

ntdll.dll!_RtlpCoalesceFreeBlocks@16()  + 0x35 bytes    
ntdll.dll!_RtlFreeHeap@12()  + 0x91f bytes  
msvcr90.dll!_free()  + 0xcd bytes   
msvcp90.dll!std::locale::`scalar deleting destructor'()  + 0x19 bytes   
msvcp90.dll!std::ios_base::_Ios_base_dtor()  + 0x39 bytes   
msvcp90.dll!std::basic_stringstream<char,std::char_traits<char>,std::allocator<char> >::`vbase destructor'()  + 0x19 bytes  
asapGeneric.dll!asap::FieldValueMessage::Get(const std::basic_string<char,std::char_traits<char>,std::allocator<char> > & field="ASK", double & value=0.055000000000000000)  Line 33 + 0x17 bytes   C++
_hdf.pyd!asap::TradeAndQuoteNormalizer::ParseQuote(asap::FieldValueMessage * msg=0x027194c0, asap::TAQ * taq=0x02716908)  Line 84 + 0x36 bytes  C++

value of field is “ASK”.

This code has been running fine without any issues, but now i am getting exception on “return true” statement.

when i debug though the program… sstr.fail() returns false. The pointer comes on return true; statement. At this point when i do a single step, suddenly I get Unhandled exception: Access violation reading from location xxxxx. I have never seen an exception on a return statement. What is incorrect in this case? This c++ program is called from a python script.

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1 Answer

  1. Editorial Team

    Answer to above post is really an collections of comments on the question. more than one replies helped me find the solution. The problem in above case was that I did not initialize the staging data properly. It was expected to be an array of size same as quote_fields but it was initialized to length 1. So first element was updated correctly but during the second element in quote_fields array is bring read, i was getting above exception.
    Apparantly exception is not raised as soon as i try to access incorrect element. Exception is comin from stringstream destructor. As per Retired Ninja, the exception is not raised immediately but only until heap tries to merge 2 free blocks at a later point as shown in the call stack.

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