获取数组中字符串的索引列表？

Question

我有一个数组：

string[] cars = {"Volvo", "BMW", "Volvo", "Mazda","BMW","BMW"};

我正在寻找宝马的索引，我使用下面的代码来获得：

Label1.Text = Array.FindIndex(filterlistinput, x => x.Contains("BMW")).ToString();

不幸的是，它只返回第一个 BMW 指数的结果。电流输出：

 1

我的预期输出将是

{1,4,5}

Answer 1

您可以执行以下操作

string[] cars = { "Volvo", "BMW", "Volvo", "Mazda", "BMW", "BMW" };
// Get indices of BMW 
var indicesArray = cars.Select((car, index) => car == "BMW" ? index : -1).Where(i => i != -1).ToArray();
// Display indices
Label1.Text = string.Join(", ", indicesArray);

Answer 2

您可以尝试以下方法，

string[] cars = {"Volvo", "BMW", "Volvo", "Mazda","BMW","BMW"};
//returns **{1,4,5}** as a list
var res = Enumerable.Range(0, cars.Length).Where(i => cars[i] == "BMW").ToList();
//joined items of list as 1,4,5
Label1.Text = string.Join(",", res);