blocks|key|1269243|text|只需指向给定键处的字典，并分配一个新值：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1269244|myDictionary[myKey]+=+myNewValue;|code-block|syntax|javascript|1269245|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Just point to the dictionary at given key and assign a new value:

<pre><code>myDictionary[myKey] = myNewValue;
</code></pre>

blocks|key|1269314|text|您可以遵循以下方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1269315|void+addOrUpdate(Dictionary<int,+int>+dic,+int+key,+int+newValue)
{
++++int+val;
++++if+(dic.TryGetValue(key,+out+val))
++++{
++++++++//+yay,+value+exists!
++++++++dic[key]+=+val+%2B+newValue;
++++}
++++else
++++{
++++++++//+darn,+lets+add+the+value
++++++++dic.Add(key,+newValue);
++++}
}|code-block|syntax|javascript|1269316|你在这里得到的优势是，你只需一次访问字典就可以检查并获得相应键的值。如果您使用ContainsKey检查是否存在，并使用dic[key]+=+val+%2B+newValue;更新值，那么您将访问字典两次。|offset|length|style|CODE|1269317|entityMap^0|0|0|13|B|1O|Q|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

You can follow this approach:

<pre><code>void addOrUpdate(Dictionary&lt;int, int&gt; dic, int key, int newValue)
{
 int val;
 if (dic.TryGetValue(key, out val))
 {
 // yay, value exists!
 dic[key] = val + newValue;
 }
 else
 {
 // darn, lets add the value
 dic.Add(key, newValue);
 }
}
</code></pre>

The edge you get here is that you check and get the value of corresponding key in just 1 access to the dictionary. 
If you use <code>ContainsKey</code> to check the existance and update the value using <code>dic[key] = val + newValue;</code> then you are accessing the dictionary twice.

blocks|key|1269326|text|使用LINQ:访问键的字典并更改值|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1269327|Dictionary<string,+int>+dict+=+new+Dictionary<string,+int>();
dict+=+dict.ToDictionary(kvp+=>+kvp.Key,+kvp+=>+kvp.Value+%2B+1);|code-block|syntax|javascript|1269328|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use LINQ: Access to dictionary for the key and change the value

<pre><code>Dictionary&lt;string, int&gt; dict = new Dictionary&lt;string, int&gt;();
dict = dict.ToDictionary(kvp =&gt; kvp.Key, kvp =&gt; kvp.Value + 1);
</code></pre>

blocks|key|1483828|text|下面是一种通过索引进行更新的方法，非常类似于foo[x]+=+9，其中x是键，9是值|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1483829|var+views+=+new+Dictionary<string,+bool>();

foreach+(var+g+in+grantMasks)
{
++++string+m+=+g.ToString();
++++for+(int+i+=+0;+i+<=+m.Length;+i%2B%2B)
++++{
++++++++views[views.ElementAt(i).Key]+=+m[i].Equals('1')+?+true+:+false;
++++}
}|code-block|syntax|javascript|1483830|entityMap^0|M|A|Z|1|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Here is a way to update by an index much like <code>foo[x] = 9</code> where <code>x</code> is a key and 9 is the value

<pre><code>var views = new Dictionary&lt;string, bool&gt;();

foreach (var g in grantMasks)
{
 string m = g.ToString();
 for (int i = 0; i &lt;= m.Length; i++)
 {
 views[views.ElementAt(i).Key] = m[i].Equals('1') ? true : false;
 }
}
</code></pre>

blocks|key|1483970|text|这个简单的检查将执行upsert，即更新或创建。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1483971|if(!dictionary.TryAdd(key,+val))
{
++++dictionary[key]+=+val;
}|code-block|syntax|javascript|1483972|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This simple check will do an upsert i.e update or create.
<pre><code>if(!dictionary.TryAdd(key, val))
{
 dictionary[key] = val;
}
</code></pre>

blocks|key|1483902|text|这可能对你有用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1483903|场景1:原始类型|1483904|string+keyToMatchInDict+=+"x";
int+newValToAdd+=+1;
Dictionary<string,int>+dictToUpdate+=+new+Dictionary<string,int>{"x",1};

if(!dictToUpdate.ContainsKey(keyToMatchInDict))
+++dictToUpdate.Add(keyToMatchInDict+,newValToAdd+);
else
+++dictToUpdate[keyToMatchInDict]+=+newValToAdd;+//or+you+can+do+operations+such+as+...dictToUpdate[keyToMatchInDict]+%2B=+newValToAdd;|code-block|syntax|javascript|1483905|场景2:我将列表作为值使用的方法|1483906|int+keyToMatch+=+1;
AnyObject+objInValueListToAdd+=+new+AnyObject("something+for+the+Ctor")
Dictionary<int,List<AnyObject>+dictToUpdate+=+new+Dictionary<int,List<AnyObject>();+//imagine+this+dict+got+initialized+before+with+valid+Keys+and+Values...

if(!dictToUpdate.ContainsKey(keyToMatch))
+++dictToUpdate.Add(keyToMatch,new+List<AnyObject>{objInValueListToAdd});
else
+++dictToUpdate[keyToMatch]+=+objInValueListToAdd;|1483907|希望这对需要帮助的人有用。|1483908|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

This may work for you:

Scenario 1: primitive types

<pre><code>string keyToMatchInDict = "x";
int newValToAdd = 1;
Dictionary&lt;string,int&gt; dictToUpdate = new Dictionary&lt;string,int&gt;{"x",1};

if(!dictToUpdate.ContainsKey(keyToMatchInDict))
 dictToUpdate.Add(keyToMatchInDict ,newValToAdd );
else
 dictToUpdate[keyToMatchInDict] = newValToAdd; //or you can do operations such as ...dictToUpdate[keyToMatchInDict] += newValToAdd;
</code></pre>

Scenario 2: The approach I used for a List as Value

<pre><code>int keyToMatch = 1;
AnyObject objInValueListToAdd = new AnyObject("something for the Ctor")
Dictionary&lt;int,List&lt;AnyObject&gt; dictToUpdate = new Dictionary&lt;int,List&lt;AnyObject&gt;(); //imagine this dict got initialized before with valid Keys and Values...

if(!dictToUpdate.ContainsKey(keyToMatch))
 dictToUpdate.Add(keyToMatch,new List&lt;AnyObject&gt;{objInValueListToAdd});
else
 dictToUpdate[keyToMatch] = objInValueListToAdd;
</code></pre>

Hope it's useful for someone in need of help.

blocks|key|1269383|text|此扩展方法允许匹配谓词委托作为字典键选择器，并允许单独的委托执行字典值替换，因此它对所使用的键/值对的类型是完全开放的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1269384|public+static+void+UpdateAll<TKey,+TValue>(this+IDictionary<TKey,+TValue>+dictionary,+Func<TKey,+TValue,+bool>+matchPredicate,+Func<TValue,+TValue>+updatePredicate)
{
++var+keys+=+dictionary.Keys.Where(k+=>+matchPredicate(k,+dictionary[k])).ToList();
++foreach+(var+key+in+keys)
++{
++++dictionary[key]+=+updatePredicate(dictionary[key]);
++}
}|code-block|syntax|javascript|1269385|示例用法：|1269386|++++Dictionary<int,+string>+dict+=+new+Dictionary<int,+string>();
++++dict.Add(1,+"One");
++++dict.Add(2,+"Two");
++++dict.Add(3,+"Three");

++++//Before
++++foreach(var+kvp+in+dict){
++++++Console.WriteLine(kvp.Value);
++++}

++++dict.UpdateAll(
++++++++matchPredicate:+(k,+v)+=>+k+>=+2,+//Update+any+dictionary+value+where+the+key+is+>=+2
++++++++updatePredicate:+(v)+=>+v+=+v+%2B+"+is+greater+than+One"
++++++);

++++//After
++++foreach(var+kvp+in+dict){
++++++Console.WriteLine(kvp.Value);
++++}|1269387|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

This extension method allows a match predicate delegate as the dictionary key selector, and a separate delegate to perform the dictionary value replacement, so it's completely open as to the type of key/value pair being used:
<pre><code>public static void UpdateAll&lt;TKey, TValue&gt;(this IDictionary&lt;TKey, TValue&gt; dictionary, Func&lt;TKey, TValue, bool&gt; matchPredicate, Func&lt;TValue, TValue&gt; updatePredicate)
{
 var keys = dictionary.Keys.Where(k =&gt; matchPredicate(k, dictionary[k])).ToList();
 foreach (var key in keys)
 {
 dictionary[key] = updatePredicate(dictionary[key]);
 }
}
</code></pre>
Example usage:
<pre><code> Dictionary&lt;int, string&gt; dict = new Dictionary&lt;int, string&gt;();
 dict.Add(1, &quot;One&quot;);
 dict.Add(2, &quot;Two&quot;);
 dict.Add(3, &quot;Three&quot;);

 //Before
 foreach(var kvp in dict){
 Console.WriteLine(kvp.Value);
 }

 dict.UpdateAll(
 matchPredicate: (k, v) =&gt; k &gt;= 2, //Update any dictionary value where the key is &gt;= 2
 updatePredicate: (v) =&gt; v = v + &quot; is greater than One&quot;
 );

 //After
 foreach(var kvp in dict){
 Console.WriteLine(kvp.Value);
 }
</code></pre>

How to update value for a specific key in a dictionary <code>Dictionary&lt;string, int&gt;</code>?

How to update the value stored in Dictionary in C#?

如何更新字典Dictionary<string, int>中特定键的值

问如何在C#中更新字典中存储的值？
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