如何在没有 linq 的情况下获取 List<> 中元素的计数

Question

我想计算数组中的元素但没有 linq

例子：

string a = "cat";

string b = "dog";

string c = "cat";

string d = "horse";

var list = new List<string>();

list.Add(a);

list.Add(b);

list.Add(c);

list.Add(d);

期望的结果是：猫=2，狗=1，马=1

Answer 1

这是我可以考虑使用的一种方法Dictionary<string, int>：public static Dictionary<string, int> GetObjectCount(List<string> items){&nbsp; &nbsp; // Dictionary object to return&nbsp; &nbsp; Dictionary<string, int> keysAndCount = new Dictionary<string, int>();&nbsp; &nbsp; // Iterate your string values&nbsp; &nbsp; foreach(string s in items)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; // Check if dictionary contains the key, if so, add to count&nbsp; &nbsp; &nbsp; &nbsp; if (keysAndCount.ContainsKey(s))&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; keysAndCount[s]++;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; else&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // Add key to dictionary with initial count of 1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; keysAndCount.Add(s, 1);&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp;}&nbsp; &nbsp;return keysAndCount;}然后取回结果并打印到控制台：Dictionary<string, int> dic = GetObjectCount(list);//Print to Consoleforeach(string s in dic.Keys){&nbsp; &nbsp;Console.WriteLine(s + " has a count of: " + dic[s]);}

Answer 2

我不知道你为什么要为此寻找 LINQ less 的解决方案，因为这可以很容易和有效地完成。我强烈建议您使用它并按照以下方式操作：var _group = list.GroupBy(i => i);string result = "";foreach (var grp in _group)&nbsp; &nbsp;result += grp.Key + ": " + grp.Count() + Environment.NewLine;MessageBox.Show(result);否则，如果你真的无法使用 LINQ，你可以像下面那样做：Dictionary<string, int> listCount = new Dictionary<string, int>();foreach (string item in list)&nbsp; &nbsp; if (!listCount.ContainsKey(item))&nbsp; &nbsp; &nbsp; &nbsp; listCount.Add(item, 1);&nbsp; &nbsp; else&nbsp; &nbsp; &nbsp; &nbsp; listCount[item]++;string result2 = "";foreach (KeyValuePair<string, int> item in listCount)&nbsp; &nbsp; result2 += item.Key + ": " + item.Value + Environment.NewLine;MessageBox.Show(result2);

Answer 3

你可以尝试这样的事情：public int countOccurances(List<string> inputList, string countFor){&nbsp; &nbsp; // Identifiers used are:&nbsp; &nbsp; int countSoFar = 0;&nbsp; &nbsp; // Go through your list to count&nbsp; &nbsp; foreach (string listItem in inputList)&nbsp;&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp;// Check your condition&nbsp; &nbsp; &nbsp; &nbsp;if (listItem == countFor)&nbsp;&nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;countSoFar++;&nbsp; &nbsp; &nbsp; &nbsp;}&nbsp; &nbsp; }&nbsp; &nbsp; // Return the results&nbsp; &nbsp; return countSoFar;}这将为您提供任何刺痛的计数。一如既往，有更好的方法，但这是一个好的开始。或者如果你想要：public string countOccurances(List<string> inputList, string countFor){&nbsp; &nbsp; // Identifiers used are:&nbsp; &nbsp; int countSoFar = 0;&nbsp;&nbsp; &nbsp; string result = countFor;&nbsp; &nbsp; // Go through your list to count&nbsp; &nbsp; foreach (string listItem in inputList)&nbsp;&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp;// Check your condition&nbsp; &nbsp; &nbsp; &nbsp;if (listItem == countFor)&nbsp;&nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;countSoFar++;&nbsp; &nbsp; &nbsp; &nbsp;}&nbsp; &nbsp; }&nbsp; &nbsp; // Return the results&nbsp; &nbsp; return countFor + " = " countSoFar;}或者更好的选择：private static void CountOccurances(List<string> inputList, string countFor)&nbsp;{&nbsp; &nbsp; int result = 0;&nbsp; &nbsp; foreach (string s in inputList)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; if (s == countFor)&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; result++;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; &nbsp; Console.WriteLine($"There are {result} occurrances of {countFor}.");}