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java - 我的关于带有阶乘的 for 循环的 Java 代码无法正常工作

问题描述

我的Java代码应该让用户输入一个数字，然后计算该数字的阶乘，我需要使用“for循环”当我输入数字5时它告诉我阶乘是6，而它应该是120。我试过看带有分解循环的教程，但它们不起作用，我认为这是因为我有“do”命令从调用中获取值

这是代码：

static Scanner kboard = new Scanner(System.in); //variable to read in values

public static void main(String[] args) {
  int choice = 0;
  String dummy = "";
  String forename = "";
  String surname = "";
  int number = 0;



  do {

    System.out.println("1. display the user name, 2. calculate factorial, 3. exit");
    choice = kboard.nextInt();
    dummy = kboard.nextLine(); //strips out the return 

    if (choice == 1) {
      forename = getforename();
      surname = getsurname();
      displaydetails(forename, surname);
    }

    if (choice == 2) {
      number = getnumber();
      calcfactorial(number);
    }

    if (choice == 3) {
      System.out.println("bye");
    }

  } while (choice != 3);
}


public static String getforename() {

  String newforename = "";

  System.out.println("Please enter your forename ?");
  newforename = kboard.next();
  return (newforename);
} // end getforename

public static String getsurname() {
  /*
  Code to prompt the user to enter a surname
  */
  String newsurname = "";

  System.out.println("Please enter your surname ?");
  newsurname = kboard.next();
  return (newsurname);
} // end getsurname


public static void displaydetails(String displayforename, String displaysurname) {
  /*
  Code will carry out prescribed changes and display the result
  */
  char displayinitial;
  String displayusername = "";

  displaysurname = displaysurname.toUpperCase();
  displayinitial = displayforename.charAt(0);
  displayusername = displayinitial + displaysurname;
  System.out.println("Your username is " + displayusername);

}



public static int getnumber() {


  System.out.println("What numbers factorial do you want to know?");
  int newnumber = kboard.nextInt();
  return newnumber;
}

public static void calcfactorial(int newnumber) {
  int count = 0;
  int factorial = 1;

  if (newnumber > 0) {
    for (count = 1; count <= newnumber; count++); {

      factorial = factorial * count;
      System.out.println("Factorial of " + newnumber + " is: " + factorial);

    }

  } else {
    System.out.println("Number must be positive");

  }

}

标签： javaloopsfor-loopfactorial

解决方案

如果您使用过调试器，那么您可以看出它只在calcfactorial方法中执行了一次乘法，并且count已经6在这一点上。原因：

for首先，删除条件循环末尾的分号。它充当for循环的主体。这使得count等于newnumber + 1或6。

其次，在循环结束后移动您的打印语句for，但仍在if块内。否则你会得到newnumber打印输出的行。

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