Factorial in C

int fact(int n) {
     int sofar = 1;
     while (n > 0) sofar *= n--;
     return sofar;
}

Factorial in Java

public class MyInt {
  private int value;
  public MyInt (int value) {
    this.value=value;
  }
  public int getValue() {
    return value;
  }
  public MyInt getFact() {
    return new MyInt(fact(value));
  }
  private int fact(int n) {
    int sofar = 1;
    while (n>1) sofar *= n--;
    return sofar;
  }
}

Factorial in COMMON LISP

(defun fact (x)
  (if (<= x 0)
     1
     (* x (fact (- x 1)))
  )
)

Factorial in Prolog

fact(1,1).

fact(X,Fact) :-
   is X-1,
  (NewX, NF),
   is X * NF.