Just a simple character to integer conversion function with bounds checking

Safeatoi.cpp

template<typename T> T safeatoi(const char *buffer, size_t len)
{
  T returnval = 0;
  
  // parse each char and get the int value.
  for (size_t i = 0; i < len; ++i)
  {
      char ch = buffer[i];
      T value = ch - '0';
      
      if (value >= 0 && value <= 9)
          returnval = returnval * 10 + value;
  }
  
  return returnval;
}