Debugging Memory Errors with Custom Allocators
By Cristian Vlasceanu, April 01, 2002
Allocators may be weird, but it's a Good Weird. With a little help from your operating system, they can even find memory access errors.
April 2002/Debugging Memory Errors with Custom Allocators/Listing 4
typedef map<int, string> MapType;
// This function corrupts the memory
void offender(const void* ptr)
{
const char trash[] = "TRASH THE MEMORY";
::memcpy(const_cast<void*>(ptr), trash, sizeof(trash));
}
// Prints map element. Although the code
// is correct, the function may crash when
// invoked from the main program
void printElem(const MapType& m, int i)
{
MapType::const_iterator iter(m.find(i));
if (iter != m.end())
cout << iter->second << endl;
else
cout << "element not found" << endl;
}
int main()
{
MapType m;
// Initialize the map
m.insert(MapType::value_type(1, "one"));
m.insert(MapType::value_type(2, "two"));
offender(&(m.find(1)->second));
printElem(m, 1);
return 0;
}
— End of Listing —
