一个正整数的阶乘(英语:factorial)是所有小于及等于该数的正整数的积,并且有0的阶乘为1。自然数n的阶乘写作n!。
亦即n!=1×2×3×...×n。阶乘亦可以递归方式定义:0!=1,n!=(n-1)!×n。
以下实例演示了 Java 阶乘代码的实现:
/* author by dba.cn MainClass.java */ public class MainClass { public static void main(String args[]) { for (int counter = 0; counter <= 10; counter++){ System.out.printf("%d! = %d\n", counter, factorial(counter)); } } public static long factorial(long number) { if (number <= 1) return 1; else return number * factorial(number - 1); } }
以上代码运行输出结果为:
0! = 1 1! = 1 2! = 2 3! = 6 4! = 24 5! = 120 6! = 720 7! = 5040 8! = 40320 9! = 362880 10! = 3628800