[英]Using loops to compute factorial numbers, Java
I'm trying to compute the value of 7 factorial and display the answer, but when I tried to look up a way to do this I kept finding code that was written so that a number first had to be put in from the user and then it would factor whatever number the user put in. But I already know what number I need, obviously, so the code is going to be different and I'm having trouble figuring out how to do this. 我正在尝试计算7阶乘的值并显示答案,但是当我尝试寻找一种方法来执行此操作时,我一直在寻找编写的代码,因此必须首先从用户输入一个数字,然后再输入它会考虑用户输入的数字。但是很明显,我已经知道我需要多少数字,因此代码将有所不同,并且我很难确定如何执行此操作。
I tried this at first 我一开始尝试了
public class Ch4_Lab_7
{
public static void main(String[] args)
{
int factorial = 7;
while (factorial <= 7)
{
if (factorial > 0)
System.out.println(factorial*facto…
factorial--;
}
}
}
But all it does is display 7*7, then 6*6, then 5*5, and so on, and this isn't what I'm trying to do. 但是它所做的只是显示7 * 7,然后是6 * 6,然后是5 * 5,依此类推,这不是我想要的。 Does anyone know how to do it correctly?
有人知道如何正确地做吗?
import java.util.Scanner;
public class factorial {
public static void main (String[] args) {
Scanner input = new Scanner(System.in);
//Gives Prompt
System.out.print("Enter a number to find the factorial of it");
//Enter the times you want to run
int number = input.nextInt();
//Declares new int
int factor = 1;
//Runs loop and multiplies factor each time runned
for (int i=1; i<=number; i++) {
factor = factor*i;
}
//Prints out final number
System.out.println(factor);
}
}
Just keep multiplying it and until it reaches the number you inputted. 只需不断乘以它,直到达到您输入的数字。 Then print.
然后打印。
Input:5 Output:120 输入:5输出:120
input:7 Output:5040 输入:7输出:5040
You need to have two variables, one for the factorial calculation and other for the purpose of counter. 您需要有两个变量,一个用于阶乘计算,另一个用于计数器。 Try this, i have not tested it but should work:
试试这个,我还没有测试过,但是应该可以工作:
public static void main(String[] args)
{
int input = 7;
int factorial = 1;
while (input > 0)
{
factorial = factorial * input
input--;
}
System.out.println("Factorial = " + factorial);
}
int a=7, fact=1, b=1;
do
{
fact=fact*b;//fact has the value 1 as constant and fact into b will be save in fact to multiply again.
System.out.print(fact);
b++;
}
while(a>=b); // a is greater and equals tob.
1st reason: The methods you seen are probably recursive, which you seem to have edited. 第一个原因:您看到的方法可能是递归的,您似乎已经对其进行了编辑。
2nd: You are not storing, ANYWHERE the temporal results of factorial. 第二:无论何处,您都不会存储阶乘的时间结果。
Try this 尝试这个
//number->n for n!
int number = 7;
//We'll store here the result of n!
int result = 1;
//we start from 7 and count backwards until 1
while (number > 0) {
//Multiply result and current number, and update result
result = number*result;
//Update the number, counting backwards here
number--;
}
//Print result in Screen
System.out.println(result);
Try this: 尝试这个:
public static void main(String args[]) {
int i = 7;
int j = factorial(i); //Call the method
System.out.println(j); //Print result
}
public static int factorial(int i) { //Recursive method
if(i == 1)
return 1;
else
return i * factorial(i - 1);
}
This would print out the factorial of 7. 这将打印出阶乘为7。
public class Factorial {
public static void main(String[] args) {
int result = factorial(5); //this is where we do 5!, to test.
System.out.println(result);
}
public static int factorial(int n) {
int x = 1;
int y = 1;
for (int i = 1; i <= n; i++) {
y = x * i;
x = y;
}
return y;
}
} }
/*so, for 3! for example, we have:
i=1:
y = x * i, where x = 1, so that means:
y = 1*1 ; y= 1; x = y so x = 1. Then i increments =>
i = 2:
y = x * i. x is 1 and i is 2, so we have y = 2. Next step in code: x=y, means x = 2. Then i increments =>
i = 3:
y = x *i so we have y = 2*3. y=6. */
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