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 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...

Convert a String to an Int Array The String represents text as a sequence of UTF-16 code units. The String is a sequential collection of characters that is used to represent text. The String is a sequential collection of System.Char objects. The following .net c# tutorial code demonstrates how we can convert a String object to an Int Array. In this .net c# tutorial code we will initialize a String instance in which content is int values separated by commas. We will split the String object into a String Array then we will create an Int array from this String Array. The String Split(Char[], StringSplitOptions) method splits a String into substrings based on specified delimiting characters and String split options. Here we will remove empty entries while we split the String instance. Now, we will call Enumerable Select() method. The Enumerable Select() method projects each element of a sequence into a new form. Using this method, we convert...

Convert a String to an IP address The String represents text as a sequence of UTF-16 code units. The String is a sequential collection of characters that is used to represent text. The String is a sequential collection of System.Char objects. The following .net c# tutorial code demonstrates how we can convert a String object to an IP address. The IPAddress class provides an Internet Protocol (IP) address. IPAddress Parse(String) method overload converts an IP address String to an IPAddress instance. The IPAddress Parse(string ipString) has a required parameter named ‘ipString’. The ‘ipString’ is a String that contains an IP address in the dotted-quad notation for IPv4 and in the colon-hexadecimal notation for IPv6. The IPAddress Parse() method returns an IPAddress instance. The IpAddress Parse(ipString string) method throws ArgumentNullException if the ‘ipString’ is null. It also throws FormatException if the ‘ipString’ is not a valid ID ...

Convert a String into an int List The String represents text as a sequence of UTF-16 code units. The String is a sequential collection of characters that is used to represent text. The String is a sequential collection of System.Char objects. The following .net c# tutorial code demonstrates how we can convert a String instance into an int List object. So, in this .net c# tutorial code we will split a String instance into a String Array then we will convert the String Array into an int data type List object. Here we will split a String whose contents are numbers and they are separated by the comma delimiter. The String Split(Char[], StringSplitOptions) method splits a String into substrings based on specified delimiting characters and String split options. In this example .net c# code, we removed the empty entries using the String split options StringSplitOptions.RemoveEmptyEntries. So, using the Split(Char[], StringSplitOptions) method we can sp...

Get bytes from a String The String represents text as a sequence of UTF-16 code units. The String is a sequential collection of characters that is used to represent text. The String is a sequential collection of System.Char objects. The following .net c# tutorial code demonstrates how we can get bytes from a String instance. Here we will use ASCII, Default, and UTF8 encoding and Encoding class GetBytes() method. The Encoding class represents the character encoding. Encoding is the process of transforming a set of Unicode characters into a sequence of bytes and decoding is the process of transforming a sequence of encoded bytes into a set of Unicode characters. The Encoding ASCII property gets an encoding for the ASCII (7-bit) character set. The Encoding Default property gets the default encoding for this .NET implementation and the Encoding UTF8 property gets an encoding for the UTF-8 format. The Encoding GetBytes() method when ove...