阶乘 Java 程序
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Factorial Java Program
提问by Eqorip
I want to do a factorial program in java using a for loop. For example I want to take the user input, lets say 10, and then multiply 10*9*8*7*6*5*4*3*2*1. I need help constructing the forloop. The code below is all I have so far as I'm not sure where to go after.
我想使用for循环在java中做一个阶乘程序。例如，我想接受用户输入，比如说10，然后乘以10*9*8*7*6*5*4*3*2*1。我需要帮助构建for循环。下面的代码是我目前所拥有的所有代码，因为我不知道该去哪里。
import java.util.Scanner;
import java.lang.Math;
public class factorial {
public static void main(String[] args) {
int num;
Scanner input = new Scanner(System.in);
System.out.println("Enter a number: ");
num = input.nextInt();
}
}
采纳答案by laaposto
Try
尝试
public static void main(String[] args) {
int num;
int fact=1;
Scanner input = new Scanner(System.in);
System.out.println("Enter a number: ");
num = input.nextInt();
for (int i=2;i<=num; i++){
fact=fact*i;
}
System.out.println("Factorial: "+fact);
}
As @Marko Topolnik mentioned in comments this code will work for inputs up to 12. For larger inputs will output infinity due to overflow.
正如@Marko Topolnik 在评论中提到的，此代码适用于最多 12 的输入。对于更大的输入，由于溢出将输出无穷大。
For numbers larger than 12 you should use higher data type like BigInteger
对于大于 12 的数字，您应该使用更高的数据类型，例如 BigInteger
You can try:
你可以试试：
public static void main(String[] args) {
BigInteger num;
BigInteger fact = BigInteger.valueOf(1);
Scanner input = new Scanner(System.in);
System.out.println("Enter a number: ");
num = input.nextBigInteger();
for (int i = 2; i <= num; i++){
fact = fact.multiply(BigInteger.valueOf(i));
}
System.out.println(fact);
}
回答by Craig Manson
int sum = 1;
for (int i = 2;i <= num;i++) {
sum = sum * i;
}
回答by Fabinout
Why bother computing it?
为什么要费心计算呢？
public int factorial ( int n ) {
switch(n){
case 0: return 1;
case 1: return 1;
case 2: return 2;
case 3: return 6;
case 4: return 24;
case 5: return 120;
case 6: return 720;
case 7: return 5040;
case 8: return 40320;
case 9: return 362880;
case 10: return 3628800;
case 11: return 39916800;
case 12: return 479001600;
default : throw new IllegalArgumentException();
}
Source : @Emory
资料来源：@埃默里
回答by Siddhesh Urkude
Try this program:=
试试这个程序：=
import java.util.*;
public class Factorials {
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
int i,num,a,b;
int c=1;
System.out.println("Enter the no.= ");
num=sc.nextInt();
for(i=1;i<=num;i++){
c=i*c;
}
System.out.println("Factorial is "+c);
}
}
回答by Merit Campus
This is My Program
这是我的程序
class FactorialUsingFor
{
public static void main(String arg[])
{
int factorial = 1;
int number = 6;
for(int i = 1; i <= number; i++)
{
factorial *= i;
}
System.out.println("Factorial of number " + number + " is " + factorial);
}
}
回答by gadolf
Coding by Recursive function:
递归函数编码：
import java.util.Scanner;
public class Main {
public static void main(String[] args)
{
System.out.print("Enter a number: ");
Scanner input = new Scanner(System.in);
int num = input.nextInt();
long factorialResult = factorialRecursive(num);
System.out.println(factorialResult);
}
public static long factorialRecursive(int n) {
if (n == 0 || n == 1 )
return 1;
return n * factorialRecursive(n - 1);
}
}
source: learn.uncox.com
If the number is large, "stackoverflow" happens.
如果数量很大，就会发生“stackoverflow”。
回答by David William
import java.util.Scanner;
public class Factorial {
public static void main(String[] args){
Scanner scn = new Scanner(System.in);
System.out.println("Enter the number to find factorial");
int o=scn.nextInt();
int count=0,b=o-1,res=(o*(o-1)),r=0;
while(count!=1)
{
count=b-1;
r=count*res;
res=r;
r=1;
b=b-1;
}
System.out.println(res);
}
}
