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I have searched but I was not able to find this. Would anyone please tell me that if there is any built-in factorial function in c++ ?

Although there is no C function defined specifically for computing factorials, C math library lets you compute gamma function. Since Г(n) = (n-1)! for positive integers, using `tgamma`

of `i+1`

yields `i!`

.

If you use a user-defined factorial function, this would print identical numbers:

`for (int i = 1 ; i != 10 ; i++) { printf("%lld %f/n", factorial(i), tgamma(i+1)); } `

`1 1.000000 2 2.000000 6 6.000000 24 24.000000 120 120.000000 720 720.000000 5040 5040.000000 40320 40320.000000 362880 362880.000000 `

**Note:** Considering how easy it is to code up factorial function, using gamma to compute factorials is a lot like killing a fly with a sledgehammer.