c＃爲什麼交集方法返回這個？

Question

我有兩個數組，數組testAnswer包含「考試答案」，數組inputAnswers包含「學生對考試的答案」。

我想顯示正確的和不正確的答案。換句話說，試圖顯示testAnswer具有那個inputAnswers的值（不正確答案），以及兩個數組的值都有共同的值（正確答案）。

爲此，我使用了使用linq的.Except和.Intersect方法;然而我越來越奇怪的輸出：

B, D, A, C 

任何人都可以請幫助我，我一直在這個很長的時間！

我的代碼：

private void button1_Click(object sender, EventArgs e) 
    { 
     string[] testAnswer = new string[20] { "B", "D", "A", "A", "C", "A", "B", 
      "A", "C", "D", "B", "C", "D", "A", "D", "C", "C", "B", "D", "A" }; 
     string a = String.Join(", ", testAnswer); 

    // Reads text file line by line. Stores in array, each line of the 
    // file is an element in the array 
     string[] inputAnswer = System.IO.File 
       .ReadAllLines(@"C:\Users\Momo\Desktop\UNI\Software tech\test.txt"); 
     string b = String.Join(", ", inputAnswer); 

     var inter = inputAnswer.Intersect(testAnswer); 
     foreach (var s in inter) 
     { 
      listBox1.Items.Add(s); 
     } 
    } 

Answer 1

Intersect確實設置相交，所以它丟棄重複的值。如果你想比較答案，更好的選擇是並行通過陣列：

for(int i=0; i<testAnswer.Length; i++) { 
    if(testAnswer[i] == inputAnswer[i]) 
     listBox1.Items.Add(inputAnswer[i]); // or testAnswer[i], as appropriate 
}