C# |获取或设置 StringDictionary 中指定键的值
原文:https://www . geesforgeks . org/c-sharp-get-or-set-value-at-specified-in-stringdictionary/
StringDictionary。项[字符串]属性 用于获取或设置与指定键关联的值。
语法:
public virtual string this[string key] { get; set; }
这里键是系统类型的键。字符串的值是获取还是设置。
返回值:该属性返回与指定键关联的值。如果没有找到指定的键，Get 返回 null ，Set 用指定的键创建一个新的条目。
异常:如果键为空，该属性抛出ArgumentNullException 。
以下程序说明了上述属性的使用:
例 1:
// C# code to get or set the value at
// the specified key in StringDictionary
using System;
using System.Collections;
using System.Collections.Specialized;
class GFG {
// Driver code
public static void Main()
{
// Creating a StringDictionary named my1
StringDictionary my1 = new StringDictionary();
// Adding key and value into the StringDictionary
my1.Add("1", "C");
my1.Add("2", "C++");
my1.Add("3", "Java");
my1.Add("4", "Python");
my1.Add("5", "C#");
// Displaying the keys and
// values in StringDictionary
foreach(DictionaryEntry d in my1)
{
Console.WriteLine(d.Key + " " + d.Value);
}
Console.WriteLine("\nAfter Item[String] Property: \n");
// setting the value at key 2
my1["2"] = "HTML";
// Displaying the keys and
// values in StringDictionary
foreach(DictionaryEntry d1 in my1)
{
Console.WriteLine(d1.Key + " " + d1.Value);
}
}
}
输出:
3 Java
5 C#
4 Python
2 C++
1 C
After Item[String] Property:
3 Java
4 Python
2 HTML
1 C
5 C#
例 2:
// C# code to get or set the value at
// the specified key in StringDictionary
using System;
using System.Collections;
using System.Collections.Specialized;
class GFG {
// Driver code
public static void Main()
{
// Creating a StringDictionary named my1
StringDictionary my1 = new StringDictionary();
// Adding key and value into the StringDictionary
my1.Add("1", "HTML");
my1.Add("2", "CSS");
my1.Add("3", "PHP");
my1.Add("4", "MongoDB");
my1.Add("5", "AngularJS");
// Displaying the keys and
// values in StringDictionary
foreach(DictionaryEntry d in my1)
{
Console.WriteLine(d.Key + " " + d.Value);
}
Console.WriteLine("\nAfter Item[String] Property: \n");
// setting the value at Key 8
// here key 8 is not present
// so it will add a new key/value
// pair. see output
my1["8"] = "C#";
// Displaying the keys and
// values in StringDictionary
foreach(DictionaryEntry d1 in my1)
{
Console.WriteLine(d1.Key + " " + d1.Value);
}
}
}
输出:
3 PHP
5 AngularJS
4 MongoDB
2 CSS
1 HTML
After Item[String] Property:
3 PHP
4 MongoDB
2 CSS
1 HTML
8 C#
5 AngularJS
参考:
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