c为什么intersect方法返回这个

Question

我有两个数组，数组testAnswer保存"考试答案"，数组inputAnswers保存"学生考试答案"。

我正在尝试显示正确和不正确的答案。换句话说，试图显示testAnswer有哪些值inputAnswers没有（错误答案），以及两个数组的共同值（正确答案）。

为此，我使用了。除了和。使用linq的求交方法；然而，我得到了这个奇怪的输出：

B, D, A, C

有人能帮帮我吗？我已经做了很长时间了！

我的代码：

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:UsersMomoDesktopUNISoftware techtest.txt");
      string b = String.Join(", ", inputAnswer);
      var inter = inputAnswer.Intersect(testAnswer);
      foreach (var s in inter)
       {
          listBox1.Items.Add(s);
        }
     }   

Answer 1

Intersect确实设置了交集，因此它会丢弃重复的值。如果你想比较答案，一个更好的选择是并行遍历数组：

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