Programming Tutorials

Dictionary to string The Dictionary class represents a collection of keys and values. .Net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object structure is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can convert a Dictionary object to a String object. To achieve this, we initially initialize an instance of an empty Dictionary object. Whose key and value data types both are String. Then we add elements (key-value pair) to the Dictionary instance. We can display the Dictionary elements on the screen (ap.net page) using a foreach loop. We initialize an empty StringBuilder object. StringBuilder object represents a mutable string of characters....

Dictionary reverse The Dictionary class represents a collection of keys and values. .Net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can reverse the Dictionary element’s position. By default a Dictionary position its elements as they were added to the collection. But the .net developers can reverse the Dictionary elements position using the .net c# built-in method. The Enumerable Reverse() method inverts the order of the elements in a sequence. The Enumerable Reverse() method returns a sequence whose elements correspond to those of the input sequence in reverse order. T...

Find duplicate values from a dictionary The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. We also can add some items to the Dictionary at the initializing time. The following .net c# tutorial code demonstrates how we can find duplicate values from a Dictionary. Dictionary keys are unique, we can’t put multiple elements in a Dictionary with the same key. But Dictionary values can be duplicated. The .net developers can set the same value to multiple elements. So, sometimes the .net developers need to find the duplicate values from a Dictionary items collection. T...

Update a key in a dictionary The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. We also can add some items to the Dictionary at the initializing time. The following .net c# tutorial code demonstrates how we can update a key in a Dictionary. We know that the Dictionary element is consist of a key and value pair. The Dictionary keys are unique and we can’t set the same key for multiple items. But the Dictionary values can be duplicated and we can set the same value for the multiple items in a Dictionary. There is no direct way to update a key for a specific item in t...

Update a value in a dictionary The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. We can initialize an empty Dictionary instance and add elements to it using its Add() method. We also can add some items to the Dictionary at the initializing time. The following .net c# tutorial code demonstrates how we can update a value in a Dictionary. Actually, this tutorial is for, how we can update a value in a specified element. Here we will update a value for a specified key. We know that the Dictionary element is consist of a key and value pair. The Dictionary keys are unique and we can’t set the same key for multiple items. But the Dictionary values can be duplicated and we can set the same value for the multiple items in a Dictionary. Updating a key in a Dictionary is difficult but we can update a value very easily. We can get an element from...

Dictionary add item if not exists The Dictionary class represents a collection of keys and values. .Net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can add an item to the Dictionary items collection if the item already not exists. A Dictionary item consists of a key and a value pair. In the entire Dictionary, the key must be unique but the value can be duplicated. So, the logic is clear, if we want to add an item to the Dictionary items collection, at first we have to check whether the item key already exists in Dictionary or not. If the item key does not exist in the Diction...

Dictionary get first key value The Dictionary class represents a collection of keys and values. .Net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can get the first key and value from a Dictionary. The .net frameworks have the built-in method to get the first key-value pair from a Dictionary instance. So the .net c# developers can easily get the first key-value pair from a Dictionary items collection. The Enumerable First() method returns the first element of a sequence. The First() method throws InvalidOperationException if the source sequence is empty. And the Enumerable Firs...

Get a key value pair from Dictionary The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can get a key-value pair from a Dictionary at a specified index position. Dictionary each item is consist of a key-value pair. So to get an item from a Dictionary also means to get a key-value pair from a Dictionary items collection. We know that in the .net framework, we can get an element from a collection very easily. The .net c# developers can get a specified element from a collection using its index position. The...

Find a key by value in a dictionary The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. We can initialize an empty Dictionary instance and add elements to it using its Add() method. We also can add some items to the Dictionary at the initializing time. The following .net c# tutorial code demonstrates how we can find a key by its value in a dictionary object. We know that the Dictionary element is consist of a key and value pair. The Dictionary keys are unique and we can’t set the same key for multiple items. But the Dictionary values can be duplicated and we can set the same value for the multiple items in a Dictionary. So, in a Dictionary object, there might be multiple items with the same value. In this situation, we will take only the first element whose value matches our criteria after finding the items. The Enumerable First() meth...

Dictionary get key by index .Net framework dictionary represents a collection of keys and values. each element of dictionary contain a key andvalue pair. so to get the dictionary key by index, first we need to find the specified element by index and then get thiselement's key. Enumerable.ElementAt<TSource> method allow us to get the element at a specified index in a sequence. this method exists in System.Linqnamespace. this method type parameter is 'TSource' which represents type of the elements of 'source'. ElementAt() method require to pass twoparameters named 'source' and 'index'. 'source' parameter type is System.Collections.Generic.IEnumerable<TSource> which representsan IEnumerable<T> to return an element from. 'index' parameter value data type is System.Int32 which represents the zero based index of theelement to retrieve. this method throw ArgumentNullException e...

Dictionary get item index by key The Dictionary class represents a collection of keys and values. .Net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can get an item index by its key from a Dictionary object. Each Dictionary item is built with a key-value pair. Dictionary keys are unique but values can be duplicated. So we can easily identify an item from a Dictionary using the specified item key. This way, we can get the Dictionary item’s index position using its item key. To achieve this, at first, we converted the Dictionary keys to a list, then we get the specified key’s ind...

Convert dictionary values to list The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can convert Dictionary values to a list. Dictionary keys are unique but the values can be duplicated. The Enumerable ToList() method creates a List<T> from an IEnumerable<T>. The ToList() method returns a List<T> that contains elements from the input sequence. The Enumerable ToList() method throws ArgumentNullException if the source is null. The Enumerable ToList() method is located in System.Linq nam...

Remove first element from dictionary The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can remove the first element from a Dictionary. The Dictionary elements are the collection of key-value pairs. So this tutorial will demonstrate how we can remove the first key-value pair from a Dictionary object. The Dictionary Remove() method removes the value with the specified key from the Dictionary<TKey,TValue>. The Remove() method has a parameter named ‘TKey key’, this is the key of the element to remove. So, i...

Dictionary TryGetValue() case insensitive The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can use Dictionary TryGetValue() method. In this .net c# tutorial code we will also demonstrate how we can use Dictionary TryGetValue() method in a case-insensitive way. So, we will pass a key in a different case instead the original case such as ‘SNOW Goose’ instead of ‘Snow Goose’. The Dictionary TryGetValue() method gets the valueAssociated with the specified key. The TryGetValue() method has two parameters named...

Sort a Dictionary by DateTime value The Dictionary class represents a collection of keys and values. The .net framework’s Dictionary is located under the System.Collections.Generic namespace. We can initialize an empty Dictionary instance and add elements to it using its Add() method. We also can add some items to the Dictionary at the initializing time. The following .net c# tutorial code demonstrates how we can sort Dictionary elements by DateTime value. How can we sort Dictionary items in ascending and descending order while their values are DateTime data type? In this .net c# tutorial code we initialize a Dictionary instance whose value data type is DateTime and the key data type is Int. We have to sort the Dictionary elements in ascending and descending order by their DateTime data type values. By default, Dictionary object holds their elements as they are added or put in initializing time. The Enumerable OrderBy() method sorts the ...

Dictionary sort order The Dictionary class represents a collection of keys and values. .Net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can sort Dictionary elements. And how .net developers can sort dictionary elements in both ascending and descending order? How .net c# developers can sort dictionary items by their keys or values. The .net c# developers can sort Dictionary items by their keys in both ascending and descending order and they also can sort Dictionary items by their values both in ascending and descending order. In the following example code, we sort Dictionary...

Dictionary add key value pair The Dictionary class represents a collection of keys and values. .Net framework’s Dictionary is located under the System.Collections.Generic namespace. The Dictionary object constructor is Dictionary<TKey,TValue>. The TKey is the data type of the keys in the Dictionary and the TValue is the data type of the values in the Dictionary. We can initialize an empty Dictionary instance and add elements to it using its Add() method. The following .net c# tutorial code demonstrates how we can add key-value pairs to a Dictionary object. Dictionary each item contains a key-value pair. So if we want to add the item to the dictionary collection we have to add a key-value pair to the Dictionary instance. The .net framework’s KeyValuePair<TKey,TValue> defines a key-value pair that can be set and retrieved. Here the Tkey is the data type of key and TValue is the data type of value of the KeyValuePair instance. So we can...

How to convert Dictionary Keys into array .Net framework Dictionary<TKey, TValue> class represents a collection of keys and values. the Dictionary<TKey, TValue>.Keysproperty allow us to get a collection containing the keys in the Dictionary<TKey, TValue>. this Keys property value type isSystem.Collections.Generic.Dictionary<TKey, TValue>.KeyCollection. to convert a dictionary keys to array, first we need to get the dictionary keys by its 'Keys' property. this property return acollection (generic list) of dictionary keys. after getting the List<T>, we can convert it to an array by List class ToArray() method. List<T>.ToArray() method allow us to copy the elements of the List<T> to a new array. so we can convert the dictionary keys into array asDictionary<TKey, TValue>.Keys.ToArray(). the following asp.net c# example code demonstrate us how can we convert dictionary keys to an array ...