在 C# 中检查 Dictionary<TKey,TValue> 是否具有指定的键
csharpserver side programmingprogramming更新于 2025/9/11 11:33:00
要检查 Dictionary<TKey,TValue> 是否具有指定的键，代码如下 −
示例
using System;
using System.Collections.Generic;
public class Demo {
public static void Main() {
Dictionary<string, string> dict =
new Dictionary<string, string>();
dict.Add("One", "John");
dict.Add("Two", "Tom");
dict.Add("Three", "Jacob");
dict.Add("Four", "Kevin");
dict.Add("Five", "Nathan");
Console.WriteLine("Count of elements = "+dict.Count);
Console.WriteLine("
Key/value pairs...");
foreach(KeyValuePair<string, string> res in dict) {
Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);
}
if (dict.ContainsKey("Three"))
Console.WriteLine("Key found!");
else
Console.WriteLine("Key isn't in the dictionary!");
dict.Clear();
Console.WriteLine("Cleared Key/value pairs...");
foreach(KeyValuePair<string, string> res in dict) {
Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);
}
Console.WriteLine("Count of elements now = "+dict.Count);
}
}
输出
这将产生以下输出 −
Count of elements = 5 Key/value pairs... Key = One, Value = John Key = Two, Value = Tom Key = Three, Value = Jacob Key = Four, Value = Kevin Key = Five, Value = Nathan Key found! Cleared Key/value pairs... Count of elements now = 0
示例
让我们看另一个例子 −
using System;
using System.Collections.Generic;
public class Demo {
public static void Main() {
Dictionary<string, string> dict = new Dictionary<string, string>();
dict.Add("One", "John");
dict.Add("Two", "Tom");
dict.Add("Three", "Jacob");
dict.Add("Four", "Kevin");
dict.Add("Five", "Nathan");
Console.WriteLine("Count of elements = "+dict.Count);
Console.WriteLine("
Key/value pairs...");
foreach(KeyValuePair<string, string> res in dict) {
Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);
}
if (dict.ContainsKey("mykey"))
Console.WriteLine("Key found!");
else
Console.WriteLine("Key isn't in the dictionary!");
dict.Clear();
Console.WriteLine("Cleared Key/value pairs...");
foreach(KeyValuePair<string, string> res in dict) {
Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);
}
Console.WriteLine("Count of elements now = "+dict.Count);
}
}
输出
这将产生以下输出 −
Count of elements = 5 Key/value pairs... Key = One, Value = John Key = Two, Value = Tom Key = Three, Value = Jacob Key = Four, Value = Kevin Key = Five, Value = Nathan Key isn't in the dictionary! Cleared Key/value pairs... Count of elements now = 0
