Useful VB functions

This page contains VB expressions that you may find useful while building your app.

We grouped several of these functions in a public app, so you can try out them out and see how they behave.

VB function: Where

The Where() function returns a zero-based array containing a subset of a string array based on a specified filter criteria.

Assume you have a variable called words defined as List(Of String) = {"apple", "banana", "cherry", "date"}.

To get the list of words that contain the letter "a", apply the Where() function as follows:

words.Where(Function(w) w.Contains("a")).ToList()

The output is {"apple", "banana", "date"}.

VB function: Select

The Select() function creates a new array that contains the results of applying a lambda expression to each element in the source array.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the list of numbers multiplied by themselves, apply the Select() function as follows:

numbers.Select(Function(n) n * n).ToArray()

The output is {1, 4, 9, 16, 25}.

VB function: Aggregate

The Aggregate() function performs calculations over all the elements in an array and returns a single value. This function can be useful in aggregating multiple values inside a column.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the sum of all the numbers in the array, apply the Aggregate() function as follows:

Dim sum = numbers.Aggregate(Function(acc, n) acc + n)

The output is 15.

VB function: Group By

The GroupBy() function groups elements in a sequence by a key selector function.

Assume you have a variable called words defined as String() = {"apple", "banana", "cherry", "date"}.

To group the words by the first letter, which is the key selector function, apply the GroupBy() function as follows:

words.GroupBy(Function(w) w(0))

The output is { {"a", "apple", "date"}, {"b", "banana"}, {"c", "cherry"} }.

VB function: Order By

The OrderBy() and OrderByDescending() functions sort elements in a sequence based on a key selector function.

Assume you have a variable called words defined as String() = {"apple", "banana", "cherry", "date"}.

To order the words by their length, which is the key selector function, apply the OrderBy() function as follows:

words.OrderBy(Function(w) w.Length).ToArray()

The output is {"date", "apple", "cherry", "banana"}.

VB function: Join

The Join() function combines elements in two sequences based on a key selector function.

Assume you have two variables:

• names defined as String() = {"John", "Jane", "Joe"}
• ages defined as Integer() = {25, 30, 35}

To combine the elements in the first sequence with the elements in the second sequence, apply the Join() function as follows:

names.Join(ages, Function(name) name(0), Function(age) age Mod 10, Function(name, age) $"{name}: {age}")

The output is {"John: 25", "Jane: 30", "Joe: 35"}.

VB function: First

The First() function returns the first element in a sequence that satisfies a specified condition.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the first even number in the sequence, apply the First() function as follows:

numbers.First(Function(n) n Mod 2 = 0)

The output is 2.

VB function: First Or Default

The FirstOrDefault() function returns the first element, or a default value if no element satisfies the condition.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the first odd number in the sequence, apply the FirstOrDefault() function as follows:

numbers.FirstOrDefault(Function(n) n Mod 2 = 1)

The output is 1.

VB function: Last

The Last() function returns the last element in a sequence that satisfies a specified condition.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the first even number in the sequence, apply the last() function as follows:

numbers.Last(Function(n) n Mod 2 = 0)

The output is 4.

VB function: Last Or Default

The LastOrDefault() function returns the last element, or a default value if no element satisfies the condition.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the first odd number in the sequence, apply the FirstOrDefault() function as follows:

numbers.LastOrDefault(Function(n) n Mod 2 = 1)

The output is 5.

VB function: Skip

The Skip() function skips a specified number of elements in a sequence.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To skip the first two elements in the sequence, apply the Skip() function as follows:

numbers.Skip(2).ToArray()

The output is {3, 4, 5}.

VB function: Skip While

The SkipWhile() function skips elements until a condition is no longer satisfied.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To skip the numbers which are lower than 3, apply the SkipWhile() function as follows:

numbers.SkipWhile(Function(n) n < 3).ToArray()

The output is {3, 4, 5}.

VB function: Take

The Take() function returns a specified number of elements from the start of a sequence.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the first three elements in the sequence, apply the Take() function as follows:

numbers.Take(3).ToArray()

The output is {1, 2, 3}.

VB function: Take While

The TakeWhile() returns elements until a condition is no longer satisfied.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To get the numbers which are lower than 4, apply the TakeWhile() function as follows:

numbers.TakeWhile(Function(n) n < 4).ToArray()

The output is {1, 2, 3}.

VB function: Any

The Any() function returns true if any element in a sequence satisfies a specified condition.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To find out if at least one number in the sequence is even, apply the Any() function as follows:

numbers.Any(Function(n) n Mod 2 = 0)

The output is true.

VB function: All

The All() returns true if all elements in a sequence satisfy a specified condition.

Assume you have a variable called numbers defined as Integer() = {1, 2, 3, 4, 5}.

To find out if all the numbers in the sequence are positive, apply the All() function as follows:

numbers.All(Function(n) n > 0)

The output is true.

VB function: Add item to list

The list function AddItemToList() adds a new item to an existing list.

To add an item to the generic list, assign it the following value:

AddItemToList(Processes.ALLDATATYPES.out_genericList, MainPage.EditGrid.NewItem)

VB function: Delete item from list

The list function DeleteItemFromList() deletes items from an existing list.

To delete an item from the generic list, assign it the following value:

DeleteItemFromList(Processes.ALLDATATYPES.out_genericList, MainPage.EditGrid.RowIndex)

VB function: Update list item at index

The list function UpdateListItemAtIndex() updates items in an existing list.

To update an item in the generic list, assign it the following value:

UpdateListItemAtIndex(Processes.ALLDATATYPES.out_genericList, MainPage.EditGrid.RowIndex, MainPage.EditGrid.SelectedItem)