c++ - How many bytes is unsigned long long? -

how many bytes unsigned long long? same unsigned long long int ?

executive summary: it's 64 bits, or larger.

unsigned long long same unsigned long long int. size platform-dependent, guaranteed c standard (iso c99) @ least 64 bits. there no long long in c89, apparently msvc supports it, it's quite portable.

in current c++ standard (issued in 2003), there no long long, though many compilers support extension. upcoming c++0x standard support , size same in c, @ least 64 bits.

you can exact size, in bytes (8 bits on typical platforms) expression sizeof(unsigned long long). if want 64 bits, use uint64_t, defined in header <stdint.h> along bunch of related types (available in c99, c++11 , current c++ compilers).