long int too short

[makosz81]

Is there anything else I can use that is bigger than long int?

[Peter87]

try long long.

[makosz81]

still too short, I want to calculate 15! up to 20!

[firedraco]

You'll need to get a bignum library for that or make your own.

[andywestken]

If you just want to calculate up to 20!, then a long long should be fine.

20!       = 2432902008176640000
LLONG_MAX = 9223372036854775807 // from limits.h 

So you've got approx 6800000000000000000 to spare.