Merge Dictionaries in C#

To merge two dictionaries in C#, you can use the Union method. This method returns a new dictionary that contains all the key-value pairs from both dictionaries. If there are duplicate keys, the values from the second dictionary will overwrite the values from the first dictionary.

Here's an example:

Dictionary<string, int> dict1 = new Dictionary<string, int>()
{
    {"A", 1},
    {"B", 2},
    {"C", 3}
};

Dictionary<string, int> dict2 = new Dictionary<string, int>()
{
    {"D", 4},
    {"E", 5},
    {"C", 6}
};

Dictionary<string, int> mergedDict = dict1.Union(dict2).ToDictionary(x => x.Key, x => x.Value);

foreach (var kvp in mergedDict)
{
    Console.WriteLine(kvp.Key + ": " + kvp.Value);
}

Output:

A: 1
B: 2
C: 6
D: 4
E: 5

To merge multiple dictionaries in C#, you can use the same Union method repeatedly on each dictionary. Here's an example that merges three dictionaries:

Dictionary<string, int> dict1 = new Dictionary<string, int>()
{
    {"A", 1},
    {"B", 2},
    {"C", 3}
};

Dictionary<string, int> dict2 = new Dictionary<string, int>()
{
    {"D", 4},
    {"E", 5},
    {"C", 6}
};

Dictionary<string, int> dict3 = new Dictionary<string, int>()
{
    {"F", 7},
    {"G", 8},
    {"B", 9}
};

Dictionary<string, int> mergedDict = dict1.Union(dict2).Union(dict3).ToDictionary(x => x.Key, x => x.Value);

foreach (var kvp in mergedDict)
{
    Console.WriteLine(kvp.Key + ": " + kvp.Value);
}

Output:

A: 1
B: 9
C: 6
D: 4
E: 5
F: 7
G: 8

To combine the keys of two dictionaries in C#, you can use the Concat method to create a sequence of key-value pairs from both dictionaries and then use the ToDictionary method to create a new dictionary that has the combined keys and a default value. Here's an example:

Dictionary<string, int> dict1 = new Dictionary<string, int>()
{
    {"A", 1},
    {"B", 2},
    {"C", 3}
};

Dictionary<string, int> dict2 = new Dictionary<string, int>()
{
    {"D", 4},
    {"E", 5},
    {"C", 6}
};

var combinedKeys = dict1.Keys.Concat(dict2.Keys).Distinct();
Dictionary<string, int> combinedDict = combinedKeys.ToDictionary(key => key, value => 0);

foreach (var kvp in combinedDict)
{
    Console.WriteLine(kvp.Key + ": " + kvp.Value);
}

Output:

A: 0
B: 0
C: 0
D: 0
E: 0

C# merge two dictionaries: Merging two dictionaries involves adding all key-value pairs from one dictionary into another.

Dictionary<string, int> dictionary1 = new Dictionary<string, int> { { "One", 1 }, { "Two", 2 } };
Dictionary<string, int> dictionary2 = new Dictionary<string, int> { { "Three", 3 }, { "Four", 4 } };

foreach (var kvp in dictionary2)
{
    dictionary1[kvp.Key] = kvp.Value;
}

Merging dictionaries with LINQ in C#: Merging dictionaries using LINQ's Concat method.

Dictionary<string, int> mergedDictionary = dictionary1.Concat(dictionary2).ToDictionary(x => x.Key, x => x.Value);

Combine multiple dictionaries into one in C#: Combining multiple dictionaries into one using the Concat method.

Dictionary<string, int> combinedDictionary = dictionaries.SelectMany(dict => dict)
                                                        .ToDictionary(pair => pair.Key, pair => pair.Value);

Dictionary union in C#: Using the Union method to perform a union operation on dictionaries.

Dictionary<string, int> unionDictionary = dictionary1.Union(dictionary2).ToDictionary(x => x.Key, x => x.Value);

Merging dictionaries and handling duplicates in C#: Merging dictionaries while handling duplicates by checking for existing keys.

foreach (var kvp in dictionary2)
{
    if (!dictionary1.ContainsKey(kvp.Key))
    {
        dictionary1[kvp.Key] = kvp.Value;
    }
}

Concatenate dictionaries in C#: Concatenating dictionaries using the Concat method.

Dictionary<string, int> concatenatedDictionary = dictionary1.Concat(dictionary2).ToDictionary(x => x.Key, x => x.Value);

C# dictionary merge with overwrite: Merging dictionaries with overwrite to replace existing values.
```
foreach (var kvp in dictionary2)
{
    dictionary1[kvp.Key] = kvp.Value;
}
```

Dictionary merge without duplicates in C#: Merging dictionaries without adding duplicate keys.

foreach (var kvp in dictionary2.Where(kvp => !dictionary1.ContainsKey(kvp.Key)))
{
    dictionary1[kvp.Key] = kvp.Value;
}

Using UnionWith method to merge dictionaries in C#: Using the UnionWith method to merge dictionaries in-place.
```
dictionary1.UnionWith(dictionary2);
```

Merge dictionaries with custom equality comparer in C#: Merging dictionaries with a custom equality comparer.

var customComparer = new MyEqualityComparer();
Dictionary<string, int> mergedDictionary = dictionary1.Concat(dictionary2).Distinct(customComparer).ToDictionary(x => x.Key, x => x.Value);