stackoverflow.com › questions › 14221612Difference between long double and double in C and C++ Apr 22, 2015 · The standard only requires that long double is at least as precise as double, so some compilers will simply treat long double as if it is the same as double. But, on most x86 chips, the 10-byte extended precision format 80-bit number is available through the CPU's floating-point unit, which provides even more precision than 64-bit double , with ...