read large files part by part in C++
// Buffer size 1 Megabyte (or any number you like)
size_t buffer_size = 1<<20;
char *buffer = new char[buffer_size];
std::ifstream fin("input.dat");
while (fin)
{
// Try to read next chunk of data
fin.read(buffer, buffer_size);
// Get the number of bytes actually read
size_t count = fin.gcount();
// If nothing has been read, break
if (!count)
break;
// Do whatever you need with first count bytes in the buffer
// ...
}
delete[] buffer;