关于变量：为什么C＃需要积分类型已经有“Var”关键字？


Why C# Need Integral Types already it has “Var” keyword?

本问题已经有最佳答案，请猛点这里访问。

这可能是个愚蠢的问题，但我真的不知道原因。

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    // i is compiled as an int
    var i = 5;

    // s is compiled as a string
    var s ="Hello";

    // a is compiled as int[]
    var a = new[] { 0, 1, 2 };

    // expr is compiled as IEnumerable<Customer>
    // or perhaps IQueryable<Customer>
    var expr =
        from c in customers
        where c.City =="London"
        select c;

    // anon is compiled as an anonymous type
    var anon = new { Name ="Terry", Age = 34 };

    // list is compiled as List<int>                            
    var list = new List<int>();

如果是这样，为什么C#需要积分类型，如int、string、int[]、List<>？如果我们只使用var关键字就可以做到这一点，那么为什么有整型呢？

另一种方式，

这些有什么区别？

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var s ="Hello";
string s ="Hello";
相关讨论

(P)特别是挤奶…(p)

  • 字母名称
  • C′35；Hasn't always had EDOCX1 commercial 0，and you can't remove keywords without utterly breaking existing code.
  • You can only use VAR in method variables-not fields，parameters，return types etc.
  • 大多数人都是快乐的类型EDOCX1音标2在瓦尔镇！Especially when the type matters and there are bytes，floats，enums，dec马尔s etc that all work with the text EDOCX1 niplication 5；I.E.EDOCX1 individual 6-why change only EDOCX1 indicatual 2
  • You can't use EDOCX1 penal 0 to specify a generic type parameter(EDOCX1 penal 10)or in a EDOCX1
  • You can't use EDOCX1 penal 12 in place of EDOCX1 penal 13
相关讨论

(P)许多人会说，这是更好的做法，写作以东X1的英文23，拉瑟而不是以东X1的英文24。There are many reasons for this，but the most compelling to me is that I can look at the code and know immediately，without stretching my brain，what type EDOCX1 individual 25.这是我的勇气集中在困难的问题上。(p)(P)In fact EDOCX1 subjective 0 sill was introduced to declare variables whose types could not easily be named.It was not introduced as a conventience，although it can be used that way.(p)

(P)The EDOCX1 original 0 Keyword is just syntactic sugar，which can only be used for local variables in methods.它仍然是一个巨大的typed变量。You can hover the mouse over it in visual studio to see what type it is.(p)(P)我们仍然需要类型作为其他方式，你会如何做DOOCX1你需要的是第16个字母(p)(P)In many cases its best to be explicit，for example when working with literals that could be a number of different types，or to increase readability.(p)

(P)EDOCX1的英文字母17和EDOCX1的英文字母18没有区别。然而，有一个巨大的区别在字母名称19和字母名称20之间。In the first case all of foo's members are accessible，in the latter it's ensured that only interface members is used.这可能是重要的，以确保行为与接口兼容，而不仅仅是具体实施。(p)(P)Also，EDOCX1 0 original can't be used to pass function arguments or to declar member variables.As of use or not to use EDOCX1 English 0，I refer to this question.(p)