簡單的功能，給予意想不到的結果

Question

所以我做一個簡單的程序來找到兩個數字之間的最大公約數（LCD），使用歐幾里德算法（http://www.math.jacobs-university.de/timorin/PM/continued_fractions.pdf，第二頁）這是很簡單的。因此，這裏是我創建的功能：

 function largest_common_divider(num1, num2) { 
      var remainder; 
      var alpha = num1; 
      var beta = num2; 

      for (i = 0; i < 100; i++) { 
       /* we want to find an "n" such that 
        n * beta <= alpha < (n + 1) * beta 

        I initiated n at 1 so that I could use n = 0 
        as the end condition for my loop */   
       for (n = 1; n <= 0; n++) { 
        if (alpha > (n * beta)) { 
         //still didn't find the n 
        } else if (alpha == (n * beta)) { 
         //Hurray! our beta is the lcd 
         n = 0; 
         return beta; 
        } else { 
         // figure out the remainder 
         // and set n = 0 to terminate the loop 
         remainder = alpha - (n - 1) * beta; 
         n = 0; 
        } 
       } 
       //If we didn't find our lcd, than the previous beta 
       //become the new alpha (largest number) and the 
       //the remainder becomes the new beta (smaller number) 
       alpha = beta; 
       beta = remainder; 
      } 
     } 

需要注意的是，在這個節目，我只希望正整數，NUM1> numb2始終。

因此，爲了測試這個功能，我做了這個：

var a = 45; var b = 15; 

    var bloopidy = largest_common_divider(a,b); 

    console.log("The largest common divider between " + a + " and " + b + " is: " + 
    bloopidy); 

期待的結果是15，但我得到的是「不確定」。我用所有的小知識，我必須調試這一點，但我不能！我需要幫助的人，任何感激。謝謝！！

Answer 1

你的第二個for循環永遠不會運行：

for (n = 1; n <= 0; n++) 

1不<= 0，這樣的條件是不正確的開始，所以不要開始循環。

這意味着您的代碼可以簡化爲：

function largest_common_divider(num1, num2) { 
     var remainder; 
     var alpha = num1; 
     var beta = num2; 

     for (i = 0; i < 100; i++) { 
      alpha = beta; 
      beta = remainder; 
     } 
    } 

這並不包含一個明確的return，因此它含蓄地返回undefined。