生成 Java 中斐波那契数列的第 N 个值

Question

这是我正在运行打印斐波那契数列的第 n 个值的程序，但我遇到了一个问题，即当我输入我定义的无效值时，它仍然运行循环方法。例如，如果我输入 0，它将打印：

“不是一个有效的数字斐波那契数列的0值为0

希望有人能指出我的错误所在，我已经检查了所有的括号，但我找不到错误的地方

//position is user input for nth position, fold2 and fnew will calculate fSequence to find value

int position, fold1, fold2, fNew, loopCount;

//telling user what program will do and stipulations on how to get program to execute correctly
System.out.println("This program will tell you the nth value of the Fibonacci sequence.");
System.out.println("Enter an integer (1 - 46):");
position = keyboard.nextInt();

fold1 = 0;
fold2 = 1; 

//setting upper parameters for limit on given positions
if (position < 1 || position > 46){
    System.out.println("Not a valid number");
} 
else {
    for (loopCount = 0; loopCount < position; loopCount++ ){
        fNew = fold1 + fold2;
        fold1 = fold2;
        fold2 = fNew;                       
    }
}

System.out.println("The " + position + " of the Fibonacci Sequence is " + fold1);

Answer 1

你的最后一个 System.out.println 在你的 else 之外，因此它总是被调用。你应该把它移到 else.

Answer 2

你得到了这条线：

 System.out.println("The " + position + " of the Fibonacci Sequence is " + fold1);

在else之后，所以它甚至在if语句之后，因此它会在所有情况下执行，最后放在else括号内。

Answer 3

你的 System.out.println("The " + position + " of the Fibonacci Sequence is " + fold1); 在 else 范围之外，因此无论条件如何都执行。

您的代码应为，

 if (position < 1 || position > 46){
        System.out.println("Not a valid number");
    } 
    else {
        for (loopCount = 0; loopCount < position; loopCount++ ){
            fNew = fold1 + fold2;
            fold1 = fold2;
            fold2 = fNew;
            System.out.println("The " + position + " of the Fibonacci Sequence is " + fold1);                       
        }
    }

生成 Java 中斐波那契数列的第 N 个值

Producing the Nth value of Fibonacci Sequence in Java

java

fibonacci