Question

此代码：

var customers = from cust in Customers
    group cust by new {cust.Country} into grouping
    select new
    {
        Country = grouping.Key.Country,
        Customers = grouping
    };

customers.ToList().ForEach(g => 
    Console.WriteLine("{0} has {1} customers: {2}", 
        g.Country, 
        g.Customers.Count(), 
        String.Join(", ",g.Customers.Select(x => "#. " + x.CompanyName).ToArray())
    ));

customers.Dump();

产生以下结果：

Argentina has 3 customers: #. Cactus Comidas para llevar, #. Océano Atlántico Ltda., #. Rancho grande
Austria has 2 customers: #. Ernst Handel, #. Piccolo und mehr
Belgium has 2 customers: #. Maison Dewey, #. Suprêmes délices
Brazil has 9 customers: #. Comércio Mineiro, #. Familia Arquibaldo, #. Gourmet Lanchonetes, #. Hanari Carnes, #. Que Delícia, #. Queen Cozinha, #. Ricardo Adocicados, #. Tradição Hipermercados, #. Wellington Importadora
Canada has 3 customers: #. Bottom-Dollar Markets, #. Laughing Bacchus Wine Cellars, #. Mère Paillarde
Denmark has 2 customers: #. Simons bistro, #. Vaffeljernet
...

如何用索引/计数替换“＃”，以便得到如下结果：

Argentina has 3 customers: 1. Cactus Comidas para llevar, 2. Océano Atlántico Ltda., 3. Rancho grande
...

Answer 1

customers.ToList().ForEach(g => Console.WriteLine("{0} has {1} customers: {2}",
    g.Country, 
    g.Customers.Count(), 
    string.Join(", ",
        g.Customers.Select((x, i) => i + ". " + x.CompanyName).ToArray())));

Answer 2

尝试制作一个int x = 0;你的linq声明之前。然后，在print，（x ++）。ToString（）。

这将使x成为一个闭包。

Answer 3

您可以执行此操作以搜索迭代器索引值：

var customers = from cust in Customers
//Get Current Index
let currIndex = Customers.IndexOf(cust)
//You can then make use of the index in the Variable currIndex

如何在LINQ选择中访问循环索引？

3 个答案: