{"id":165063,"date":"2020-10-03T20:29:56","date_gmt":"2020-10-03T12:29:56","guid":{"rendered":"http:\/\/4563.org\/?p=165063"},"modified":"2020-10-03T20:29:56","modified_gmt":"2020-10-03T12:29:56","slug":"%e4%b8%80%e4%b8%aa%e6%84%9f%e8%a7%89%e9%9a%be%e4%bb%a5%e7%90%86%e8%a7%a3%e7%9a%84%e7%9a%84-c%e4%bb%a3%e7%a0%81%e7%89%87%e6%ae%b5%ef%bc%8c%e6%83%b3%e7%9f%a5%e9%81%93%e8%bf%99%e6%98%af%e4%b8%ba","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=165063","title":{"rendered":"\u4e00\u4e2a\u611f\u89c9\u96be\u4ee5\u7406\u89e3\u7684\u7684 C#\u4ee3\u7801\u7247\u6bb5\uff0c\u60f3\u77e5\u9053\u8fd9\u662f\u4e3a\u4ec0\u4e48"},"content":{"rendered":"
\n
\n
\n

\u4e00\u4e2a\u611f\u89c9\u96be\u4ee5\u7406\u89e3\u7684\u7684 C#\u4ee3\u7801\u7247\u6bb5\uff0c\u60f3\u77e5\u9053\u8fd9\u662f\u4e3a\u4ec0\u4e48 <\/h1>\n

<\/p>\n

\n
\u8cc7\u6df1\u5927\u4f6c : richards64 <\/span> <\/i> 4<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n

Action[] foos = new Action[4]; for (int i = 0; i < 4; i++) {     funcs[i] = () => Console.Write($\"{i} \"); } foreach (var foo in foos) {     foo(); } <\/code><\/pre>\n
\u8f93\u51fa\u5982\u4e0b\uff1a<\/p>\n
4 4 4 4 <\/code><\/pre>\n
\u4e3a\u4ec0\u4e48\u8f93\u51fa\u4e0d\u662f0 1 2 3<\/code>\u800c\u662f4 4 4 4<\/code>\u5462<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (20<\/span>)        <\/div>\n
 <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : Soar360 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u95ed\u5305                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : across <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6211\u8bb0\u5f97 c \uff03 via cia \u597d\u50cf\u89e3\u91ca\u8fc7\uff0c\u8fd9\u79cd\u51fd\u6570\u7684\u5b9e\u8d28\u662f\u521b\u5efa\u4e00\u4e2a\u7c7b\uff0c\u5f15\u7528 i \u53d8\u91cf\u3002\u56e0\u5faa\u73af\u7ed3\u675f\uff0c\u5f15\u7528\u7684 i \u503c\u5c31\u53d8\u6210 4 \u4e86…                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : mengqi <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6bd4\u8f83\u5e38\u89c1\u7684\u56e0\u4e3a\u60f0\u6027\u6c42\u503c\u5bfc\u81f4\u7684\u95ee\u9898\u3002\u56e0\u4e3a Console.Write(…) \u4e0d\u662f\u5728 for (int i…) \u5faa\u73af\u5185\u6c42\u503c\uff0c\u800c\u662f\u5ef6\u8fdf\u5230\u4e86 foreach \u91cc\u9762\u6c42\u503c\uff0c\u800c\u5728\u90a3\u65f6\u53d8\u91cf i \u503c\u4e3a 4\uff0c\u56e0\u6b64 foreach \u6253\u5370\u4e86 4 \u904d i \u5c31\u662f “4 4 4 4” \u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : crella <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4e0d\u61c2 c#\uff0c\u611f\u89c9\u662f Console.Write()\u91cc\u5e76\u6ca1\u6709\u4fdd\u5b58 i \u7684\u503c\uff0c\u4ec5\u4fdd\u5b58\u4e86\u5bf9\u5176\u7684\u5f15\u7528                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : crclz <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u95ed\u5305\u7684\u77e5\u8bc6\u70b9\uff0c\u8be6\u7ec6\u7684\u53ef\u4ee5\u53c2\u8003 js                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : YenvY <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u56db\u4e2a lambda \u6355\u83b7\u4e86\u540c\u4e00\u4e2a i                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : richards64 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @across \u80fd\u5927\u6982\u8bf4\u4e0b\u5728\u54ea\u4e2a\u7ae0\u8282\u5417\uff1f\u6211\u7ffb\u7ffb\u770b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : lxilu <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 [CompilerGenerated]
    private sealed class a_0
    {
     public int i;<\/p>\n
     internal void <M>b__0()
     {
     Console.Write(string.Format(“{0} “, i));
     }
    }<\/p>\n
    public void M()
    {
     Action[] array = new Action[4];
     a_0 a_ = new a_0();
     a_.i = 0;
     while (a_.i < 4)
     {
     array[a_.i] = new Action(a_.<M>b__0);
     a_.i++;
     }
     Action[] array2 = array;
     for (int i = 0; i < array2.Length; i++)
     {
     array2[i]();
     }
    }<\/p>\n
    \u6ce8\uff1a\u4e3a\u4fbf\u4e8e\u89c2\u770b\u6709\u6539\u540d\uff1b\u7f16\u8bd1\u5668\u5b9e\u73b0\uff0c\u51c6\u786e\u89c1\u6807\u51c6\uff1b\u6765\u81ea sharplab.io \uff1b                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : hejingyuan199 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8fd9\u4e2a\u6211\u597d\u50cf\u89c9\u5f97\u5f88\u81ea\u7136\u5c31\u662f 4 4 4 4 \u3002
    \u4f46\u6211\u4e0d\u77e5\u9053\u5982\u4f55\u89e3\u91ca\u3002
    \u56e0\u4e3a\u4f60\u5728\u540e\u9762\u624d\u8c03\u7528\u7684 foo\uff0c\u90a3\u65f6\u5019 i \u5df2\u7ecf\u662f 4 \u4e86\u3002
    \u90a3\u5f53\u7136\u662f\u6253\u5370\u51fa\u5168\u662f 4 \u554a\u3002<\/p>\n
    \u6211\u5c31\u6392\u4e2a\u961f\uff0c\u770b\u770b\u5404\u4f4d\u5982\u4f55\u89e3\u91ca\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : lights <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u770b\u5177\u4f53\u7684\u8bed\u8a00\u5b9e\u73b0\u5427\uff0c\u8fd9\u4e2a\u662f\u7eaf\u7684\u786c\u6027\u77e5\u8bc6\u70b9\u4e86\uff0c\u53ea\u662f\u521a\u597d C#\u91cc\u5b9e\u73b0\u7684\u662f 8 \u6240\u8bf4\u7684\u5f62\u5f0f<\/p>\n
    \u4e0d\u8fc7\u597d\u5947\u4e3a\u5565\u662f\u8fd9\u79cd\u5b9e\u73b0\u65b9\u5f0f\uff08\u56db\u4e2a lambda \u53ea new \u4e00\u4e2a\u7c7b\uff09\u800c\u4e0d\u662f new 4 \u4e2a\u7c7b\u3002\u6709\u5927\u4f6c\u89e3\u91ca\u4e00\u4e0b\u5417\uff1f                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : lights <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @across #2 \u6709\u4ecb\u7ecd\u8fd9\u79cd\u8bbe\u8ba1\u7684\u539f\u56e0\u5417\uff1f\u56db\u4e2a labmda \u53ea new \u4e00\u4e2a\u7c7b\uff0c\u4e0d\u5e94\u8be5\u662f new 4 \u4e2a\u7c7b\u5417\uff1f\u611f\u89c9\u633a\u53cd\u76f4\u89c9\u7684                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : youla <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 Action[] foos = new Action[4];
     for (int i = 0; i < 4; i++)
     {
     foos[i] = () => Console.Write(i);
     foos[i].Invoke();
     }<\/p>\n
    \/\/0 1 2 3                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : zhuang0718 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 lambda \u8868\u8fbe\u5f0f\u7684\u539f\u56e0\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : geelaw <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @lights #11 \u663e\u7136\u8fd9\u91cc\u4e00\u5171 new \u4e86 5 \u4e2a\u4e1c\u897f\uff0c\u4e00\u4e2a\u662f\u63d0\u4f9b\u72b6\u6001\u7684\u5bf9\u8c61\uff08\u5373\u7f16\u8bd1\u5668\u751f\u6210\u7684\uff09\uff0c\u63a5\u4e0b\u6765\u6bcf\u6b21\u8d4b\u503c\u7ed9\u59d4\u6258\u7684\u65f6\u5019\u90fd new \u4e86\u4e00\u4e2a Action \u3002\u6bcf\u4e2a Action \u90fd\u5f15\u7528\u4e86\u540c\u4e00\u4e2a\u72b6\u6001\u5bf9\u8c61\u7684\u540c\u4e00\u4e2a\u65b9\u6cd5\uff0c\u81f3\u4e8e\u4e3a\u4ec0\u4e48\u540c\u4e00\u4e2a\u72b6\u6001\u5bf9\u8c61\uff0c\u8fd9\u662f\u56e0\u4e3a i \u7684 scope \u53ea\u8fdb\u5165\u4e86\u4e00\u6b21\u3002\u8fd9\u91cc\u7684 for \u5faa\u73af\u7b49\u4ef7\u4e8e<\/p>\n
    for (init; cond; next) body;<\/p>\n
    { \/\/ 1
    init;
    while (cond)
    { \/\/ 2
    body;
    goto_continue:
    next;
    } \/\/ 2
    } \/\/ 1<\/p>\n
    \u5faa\u73af\u53d8\u91cf i \u7684 scope \u662f 1\uff0c\u800c scope 1 \u53ea\u8fdb\u5165\u4e86\u4e00\u6b21\uff0c\u6240\u4ee5\u53ea\u6709\u4e00\u4e2a\u72b6\u6001\u5bf9\u8c61\u3002<\/p>\n
    \u5982\u679c\u4f60\u6539\u6210<\/p>\n
    foreach (int i in new int[] { 0,1,2,3 })<\/p>\n
    \u5219\u5728\u8f83\u65b0\u7684 C# \u7f16\u8bd1\u5668\u4e0b\u4f1a\u5f97\u5230 0 1 2 3\uff0c\u56e0\u4e3a\u8fd9\u7b49\u4ef7\u4e8e<\/p>\n
    { \/\/ 1
    var coll = new int[] { 0,1,2,3 };
    for (int idx = 0; idx < coll.Length; ++idx)
    { \/\/ 2
    int i = coll[idx];
    foos[i] = () => Console.WriteLine(i);
    } \/\/ 2
    } \/\/ 1<\/p>\n
    \u56e0\u4e3a i \u7684 scope \u53d8\u6210\u4e86 for \u7684\u91cc\u9762\uff0c\u6240\u4ee5\u4f1a\u8fdb\u5165 4 \u6b21\uff0c\u56e0\u6b64\u6709 4 \u4e2a\u4e0d\u540c\u7684\u72b6\u6001\u5bf9\u8c61\u88ab\u521b\u5efa\uff0c\u6bcf\u4e2a Action \u90fd\u4f1a\u5f15\u7528\u5404\u81ea\u72b6\u6001\u5bf9\u8c61\u7684\u65b9\u6cd5\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : lxilu <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 ECMA-334
    5th Edition\/December 2017
    C# Language Specification<\/p>\n
    12. Expressions
    12.16 Anonymous function expressions
    12.16.6 Outer variables<\/p>\n
    If a for-loop declares an iteration variable, that variable itself is considered to be declared outside of the loop.
    => i \u5728 for \u5916
    Any local variable, value parameter, or parameter array whose scope includes the lambda-expression or anonymous-method-expression is called an outer variable of the anonymous function.
    => i \u4e5f\u5728\u533f\u540d\u51fd\u6570\u5916
    A local variable is considered to be instantiated when execution enters the scope of the variable.
    => i \u4ec5\u4e00\u5b9e\u4f8b
    When an outer variable is referenced by an anonymous function, the outer variable is said to have been captured by the anonymous function.
    => \u533f\u540d\u51fd\u6570\u7528\u4e86\u90a3\u552f\u4e00 i<\/p>\n
    \u6807\u51c6\u91cc\u7684\u4f8b\u5b50\uff1a
    \u2591\u2591static D[] F() {
    \u2591\u2591\u2591\u2591D[] result = new D[3];
    \u2591\u2591\u2591\u2591for (int i = 0; i < 3; i++) {
    \u2591\u2591\u2591\u2591\u2591\u2591result[i] = () => { Console.WriteLine(i); };
    \u2591\u2591\u2591\u2591}
    \u2591\u2591\u2591\u2591return result;
    \u2591\u2591}
    only one instance of the iteration variable is captured, which produces the output:
    \u2591\u25913
    \u2591\u25913
    \u2591\u25913                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : mway <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8ddf\u53d8\u91cf\u7684\u4f5c\u7528\u57df\u6709\u5173\u7cfb\uff0ci \u662f\u6574\u4e2a for \u5faa\u73af\u4f53\u7684\u5c40\u90e8\u53d8\u91cf\uff0c\u76f8\u5f53\u4e8e\u7ed9\u533f\u540d\u59d4\u6258\u5f15\u7528\u4e86\u540c\u4e00\u4e2a\u51fd\u6570\uff0c\u53ef\u4ee5\u5148\u5c06 i \u590d\u5236\u7ed9\u5355\u6b21\u5faa\u73af\u5185\u7684\u4e34\u65f6\u53d8\u91cf\uff1a
    int n= i;
    foos[i] = () => Console.Write($”{n} “);
    \u6216\u8005\u5c06 Lambda \u8f6c\u4e3a\u6709\u53c2\u7684\uff0cfoos[i] = n => Console.Write($”{n} “);\u8c03\u7528\u65f6\u518d\u628a i \u4f20\u5165\u3002
    \u8fd8\u53ef\u4ee5\u7528\u591a\u64ad\u59d4\u6258\uff0c
    \u8fd9\u6837\u6253\u5370\u51fa\u6765\u7684\u5c31\u662f 0123 \u4e86\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : Youen <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8fd9\u4e48\u5199 Resharper \u4f1a\u9a82\u7684…<\/p>\n
    https:\/\/www.jetbrains.com\/help\/resharper\/AccessToModifiedClosure.html                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : dartabe <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4ece javascript \u6765\u770b \u53d8\u91cf\u4f5c\u7528\u57df\u7684\u539f\u56e0 \u6240\u6709\u7684 i \u53d8\u91cf\u90fd\u662f\u9876\u5c42\u4f5c\u7528\u57df\u7684 i<\/p>\n
    \u7b49\u4ef7\u4e8e<\/p>\n
    Action[] foos = new Action[4];<\/p>\n
    int I;<\/p>\n
    for (i = 0; i < 4; i++)
    {
     funcs[i] = () => Console.Write($”{i} “);
    }                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : laminux29 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8bf7\u95ee\u9898\u4e3b\u662f\u9047\u5230\u5565\u9700\u6c42\uff0c\u5199\u4e86\u8fd9\u6837\u4e00\u6bb5\u5947\u602a\u7684\u4ee3\u7801\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : xuanbg <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u56e0\u4e3a\u771f\u6b63\u6267\u884c Console.Write($”{i} “);\u4e0d\u662f\u5728 for \u5faa\u73af\u91cc\u9762\uff0c\u800c\u662f\u5728 foreach \u8fed\u4ee3\u91cc\u9762\u5440\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"
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