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.
Access violation reading location 0x02790245
Alok 2012-04-04 06:46
x->staging_data[j+1] = tmp;
- Are you sure staging_data
is long enough to hold that much data?
Addition: msg->Get((*i).c_str(),tmp)
- why are you using c_str
here? It looks like it should work fine without it - DCoder 2012-04-04 06:46
staging_data
Alok 2012-04-04 06:49
c_str()
call from msg->Get((*i).c_str(),tmp)
? Can you show any more code around the caller of Get
- DCoder 2012-04-04 07:08
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.