Lambda如何同時使用&&、|| 擷取資料

lambda and or

leo226 2021-05-23 15:09:35 ‧ 677 瀏覽

如題，若以下列範例，我若要擷取出1,3,7,8,9的資料，如何使用AND + OR來擷取資料呢？

Console.WriteLine("Start：");
var temp = new int[]{ 1,2,3,4,5,6,7,8,9};
var result = temp.Where(x => (x == 1 || x == 3) && x > 6).ToList();
result.ForEach(x =>
{
    Console.WriteLine(x);
});
Console.ReadLine();

    public class myModel
    {
        public int id { get; set; }
        public int a { get; set; }
        public int b { get; set; }
        public string c { get; set; }
        public string d { get; set; }
    }
    public class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Start：");
            List<myModel> temp = new List<myModel>();
            temp.Add(new myModel() { id = 1, a = 1, b = 0, c = "TypeA", d = "StyleA" });
            temp.Add(new myModel() { id = 2, a = 1, b = 0, c = "TypeB", d = "StyleB" });
            temp.Add(new myModel() { id = 3, a = 0, b = 1, c = "TypeB", d = "StyleB" });
            temp.Add(new myModel() { id = 4, a = 0, b = 1, c = "TypeA", d = "StyleA" });
            temp.Add(new myModel() { id = 5, a = 1, b = 1, c = "TypeB", d = "StyleA" });
            temp.Add(new myModel() { id = 6, a = 1, b = 1, c = "TypeB", d = "StyleB" });
            temp.Add(new myModel() { id = 7, a = 0, b = 0, c = "TypeB", d = "StyleB" });
            var result = temp.Where(x => (x.a == 1 || x.b == 1) && x.c == "TypeB" && x.d == "StyleB").ToList();
            result.ForEach(x =>
            {
                Console.WriteLine(x.id);
            });
            Console.ReadLine();
        }
    }

listennn08 iT邦高手 5 級 ‧ 2021-05-23 15:22:18 檢舉

你這樣的邏輯是 x = 1 或 3 且 x > 6
要改用 || x > 6

leo226 iT邦新手 4 級 ‧ 2021-05-23 16:26:33 檢舉

謝謝提點，是我範例寫錯了，修正原文程式，改寫如下，用原本|| 和 && 來測試就可以得到正確的結果了~

public class myModel
{
public int id { get; set; }
public int a { get; set; }
public int b { get; set; }
public string c { get; set; }
public string d { get; set; }
}
public class Program
{
public static void Main(string[] args)
{
Console.WriteLine("Start：");
List<myModel> temp = new List<myModel>();
temp.Add(new myModel() { id = 1, a = 1, b = 0, c = "TypeA", d = "StyleA" });
temp.Add(new myModel() { id = 2, a = 1, b = 0, c = "TypeB", d = "StyleB" });
temp.Add(new myModel() { id = 3, a = 0, b = 1, c = "TypeB", d = "StyleB" });
temp.Add(new myModel() { id = 4, a = 0, b = 1, c = "TypeA", d = "StyleA" });
temp.Add(new myModel() { id = 5, a = 1, b = 1, c = "TypeB", d = "StyleA" });
temp.Add(new myModel() { id = 6, a = 1, b = 1, c = "TypeB", d = "StyleB" });
temp.Add(new myModel() { id = 7, a = 0, b = 0, c = "TypeB", d = "StyleB" });
var result = temp.Where(x => (x.a == 1 || x.b == 1) && x.c == "TypeB" && x.d == "StyleB").ToList();
result.ForEach(x =>
{
Console.WriteLine(x.id);
});
Console.ReadLine();
}
}
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//得正確預期結果
var result = temp.Where(x => (x.a == 1 || x.b == 1) && x.c == "TypeB" && x.d == "StyleB").ToList();
Start：
2
3
6
//以下這個結果，驗證邏輯有點看不懂，為什麼結果裡會有 1, 5的結果出現？
var result = temp.Where(x => x.a == 1 || x.b == 1 && x.c == "TypeB" && x.d == "StyleB").ToList();
Start：
1
2
3
5
6

謝謝提點，是我範例寫錯了，修正原文程式，改寫如下，用原本|| 和 &amp;&amp; 來測試就可以得到正確的結果了~

public class myModel
    {
        public int id { get; set; }
        public int a { get; set; }
        public int b { get; set; }
        public string c { get; set; }
        public string d { get; set; }
    }
    public class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine(&quot;Start：&quot;);
            List&lt;myModel&gt; temp = new List&lt;myModel&gt;();
            temp.Add(new myModel() { id = 1, a = 1, b = 0, c = &quot;TypeA&quot;, d = &quot;StyleA&quot; });
            temp.Add(new myModel() { id = 2, a = 1, b = 0, c = &quot;TypeB&quot;, d = &quot;StyleB&quot; });
            temp.Add(new myModel() { id = 3, a = 0, b = 1, c = &quot;TypeB&quot;, d = &quot;StyleB&quot; });
            temp.Add(new myModel() { id = 4, a = 0, b = 1, c = &quot;TypeA&quot;, d = &quot;StyleA&quot; });
            temp.Add(new myModel() { id = 5, a = 1, b = 1, c = &quot;TypeB&quot;, d = &quot;StyleA&quot; });
            temp.Add(new myModel() { id = 6, a = 1, b = 1, c = &quot;TypeB&quot;, d = &quot;StyleB&quot; });
            temp.Add(new myModel() { id = 7, a = 0, b = 0, c = &quot;TypeB&quot;, d = &quot;StyleB&quot; });
            var result = temp.Where(x =&gt; (x.a == 1 || x.b == 1) &amp;&amp; x.c == &quot;TypeB&quot; &amp;&amp; x.d == &quot;StyleB&quot;).ToList();
            result.ForEach(x =&gt;
            {
                Console.WriteLine(x.id);
            });
            Console.ReadLine();
        }
    }
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//得正確預期結果
var result = temp.Where(x =&gt; (x.a == 1 || x.b == 1) &amp;&amp; x.c == &quot;TypeB&quot; &amp;&amp; x.d == &quot;StyleB&quot;).ToList();
Start：
2
3
6
//以下這個結果，驗證邏輯有點看不懂，為什麼結果裡會有 1, 5的結果出現？
var result = temp.Where(x =&gt; x.a == 1 || x.b == 1 &amp;&amp; x.c == &quot;TypeB&quot; &amp;&amp; x.d == &quot;StyleB&quot;).ToList();
Start：
1
2
3
5
6

修改

listennn08 iT邦高手 5 級 ‧ 2021-05-23 17:11:16 檢舉

因為你沒把 x.a == 1 || x.b == 1 括起來
所以會變成 x.a == 1 或 x.b == 1 且 x.c == TypeB、 x.d == StyleB

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