打印斐波納契數

Question

我的程序應該根據用戶輸入的內容輸出一個斐波那契數（例如，如果他們輸入7，程序將輸出13）。這部分工作。我遇到問題的部分是程序檢查以確保用戶輸入的數字是正數且小於或等於70.它應該再次要求用戶輸入，而是輸出「Fibonacci＃-1爲0「並停止。這裏是我的代碼：

import java.util.Scanner; 

public class scalvert_Fibonacci 
{ 
public static void main (String args[]) 
{ 
    Scanner input = new Scanner (System.in); 

    int sum = 0; 
    int num; 
    int f1 = 0, f2 = 0, f3 = 1; 

    System.out.print("Which Fibonacci number would you like? "); 
    num = input.nextInt(); 

    if (num == 0) 
    return 0; 

    else if (num == 1) 
    return 1; 

    while (num < 0 || num > 70) 
    { 
     System.out.print("Which Fibonacci number would you like? "); 
     num = input.nextInt(); 
    } 

     for(int i = 1; i <= num; i++) 
     { 
       f1 = f2; 
       f2 = f3; 
       f3 = f1 + f2; 
     } 
     System.out.printf("Fibonacci #%d is %d\n",num, f2); 
} 
} 

Answer 1

使用這可能會解決你的問題

if(num<0 || num>70) 
{ 
    //ask a number again 
} 
else 
{ 
    //calculate 
} 

or use this 

if(0 < num < 71) 
{ 
    //calculate 
} 
else 
{ 
    //ask for a valid number 
} 

Answer 2

我想通了。

while(num < 0 || num > 70) 
    { 
     System.out.print("Which Fibonacci number would you like? "); 
     num = input.nextInt(); 
    }