VB.Net - string

May 13, 2021 vb.net

In VB.Net, strings can be used as an array of characters, but it is more common to declare a string variable using the String keyword. T he string keyword is an alias for the System.String class.

Create a string object

You can create string objects using one of the following methods:

By assigning a string literal to a String variable by specifying a string to a string variable
By using a String class constructor by using the String class constructor
By using the string concatenation operator (-) by using the string connection operator
By retrieving a property or calling a method that returns a string by retrieving properties or calling methods that return strings
By calling a formatting method to convert a value or object to its string representation
Convert a value or object to its string representation by calling a formatting method

The following example illustrates this:

Module strings
   Sub Main()
      Dim fname, lname, fullname, greetings As String
      fname = "Rowan"
      lname = "Atkinson"
      fullname = fname + " " + lname
      Console.WriteLine("Full Name: {0}", fullname)

     'by using string constructor
      Dim letters As Char() = {"H", "e", "l", "l", "o"}
      greetings = New String(letters)
      Console.WriteLine("Greetings: {0}", greetings)

      'methods returning String
      Dim sarray() As String = {"Hello", "From", "Tutorials", "Point"}
      Dim message As String = String.Join(" ", sarray)
      Console.WriteLine("Message: {0}", message)

      'formatting method to convert a value 
      Dim waiting As DateTime = New DateTime(2012, 12, 12, 17, 58, 1)
      Dim chat As String = String.Format("Message sent at {0:t} on {0:D}", waiting)
      Console.WriteLine("Message: {0}", chat)
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following results:

Full Name: Rowan Atkinson
Greetings: Hello
Message: Hello From Tutorials Point
Message: Message sent at 5:58 PM on Wednesday, December 12, 2012

The property of the String class

The String class has two properties:

SN	The name and description of the property
1	Chars Gets the Char object at the specified location in the current String object.
2	Length Gets the number of characters in the current String object.

The name and description of the property

Chars

Gets the Char object at the specified location in the current String object.

Length

Gets the number of characters in the current String object.

The method of the String class

The String class has many ways to help you work with string objects. T he following table provides some of the most commonly used methods:

SN	Method name and description
1	Public Shared Function Compare ( strA As String, strB As String ) As Integer Public shared function comparison (strA As String, strB As String) As Integer Compare the two specified string objects and return an integer indicating their relative position in the sort order.
2	Public Shared Function Compare ( strA As String, strB As String, ignoreCase As Boolean ) As Integer Public shared function comparison (strA As String, strB As String, ignoreCase As Boolean) As Integer Compare the two specified string objects and return an integer indicating their relative position in the sort order. H owever, if the Boolean parameter is true, it ignores case.
3	Public Shared Function Concat ( str0 As String, str1 As String ) As String The common sharing function Concat (str0 As String, str1 As String) As String Connect two string objects.
4	Public Shared Function Concat ( str0 As String, str1 As String, str2 As String ) As String Public Sharing Function Concat (Str0 As String, Str1 AS String, Str2 As String) AS String Connect three string objects.
5	Public Shared Function Concat (str0 As String, str1 As String, str2 As String, str3 As String) As String public sharing function Concat (str0 As String, str1 As String, str2 As String, str3 As String) As String Connect four string objects.
6	Public Function Contains ( value As String ) As Boolean The public function contains (value as string) As Boolean Returns a value indicating whether the specified string object appears in the string.
7	Public Shared Function Copy ( str As String ) As String The common share function copies (str as a string) as String Create a new String object with the same value as the specified string.
8	pPublic Sub CopyTo ( sourceIndex As Integer, destination As Char(), destinationIndex As Integer, count As Integer ) Copy a specified number of characters from the specified location of the string object to the specified location in the Unicode character array.
9	Public Function EndsWith ( value As String ) As Boolean The common function endsWith (value as string) As Boolean Determines whether the end of the string object matches the specified string.
10	Public Function Equals ( value As String ) As Boolean The public function is equal to (value as string) As Boolean Determines the current string object and specifies whether the string object has the same value.
11	Public Shared Function Equals ( a As String, b As String ) As Boolean The common share function is equal to (A as string, B as string) As Boolean Determines whether the two specified string objects have the same value.
12	Public Shared Function Format ( format As String, arg0 As Object ) As String Public shared function format (format as string, arg0 as object) As String Replace one or more formatting items in the specified string with a string representation of the specified object.
13	Public Function IndexOf ( value As Char ) As Integer Public function IndexOf (value CHAR) As Integer Returns the zero-based index in the current string that specifies that the Unicode character first appears.
14	Public Function IndexOf ( value As String ) As Integer The common function IndexOf (value as string) As Integer Returns the zero-start index in this instance that specifies that the string first appears.
15	Public Function IndexOf ( value As Char, startIndex As Integer ) As Integer The common function IndexOf (value is char, then startIndex as an integer) As Integer Returns the zero-based index in this string that specifies the first appearance of the Unicode character, starting the search from the specified character position.
16	Public Function IndexOf ( value As String, startIndex As Integer ) As Integer The public function IndexOf (value as string, startIndex as integer) As Integer Returns the zero-based index in this instance where the specified string first appears, and begins the search at the specified character location.
17	Public Function IndexOfAny ( anyOf As Char() ) As Integer The public function IndexOfAny (anyOf is CHAR()) As Integer Returns a zero-based index that first appears in this instance of any character in the specified Unicode character array.
18	Public Function IndexOfAny ( anyOf As Char(), startIndex As Integer ) As Integer The common function IndexOfAny (anyOf is char(), then startIndex as an integer) As Integer Returns the zero-based index that first appears in this instance of any character in the specified Unicode character array, starting the search at the specified character location.
19	Public Function Insert ( startIndex As Integer, value As String ) As String The common function Insert (startIndex is an integer, the value is a string) As String Returns a new string, where the specified string is inserted into the index position specified in the current string object.
20	Public Shared Function IsNullOrEmpty ( value As String ) As Boolean The common sharing function IsNullOrEmpty (value as string) As Boolean Indicates whether the specified string is empty or empty.
21	Public Shared Function Join ( separator As String, ParamArray value As String() ) As String The common share function joins (separator as string, value ParamArray as string()) As String Connect all elements of the string array, using the separator specified between each element.
22	Public Shared Function Join ( separator As String, value As String(), startIndex As Integer, count As Integer ) As String The common share function joins (separator as string, value as string (), startIndex integer, count as integer) As String Connect the specified elements of the string array with a separator specified between each element.
23	Public Function LastIndexOf ( value As Char ) As Integer The common function LastIndexOf (value CHAR) As Integer Returns the zero-based index position in the current string object that specifies the last time the Unicode character appeared.
24	Public Function LastIndexOf ( value As String ) As Integer The common function LastIndexOf (value as string) As Integer Returns the zero-based index position in the current string object that specifies the last time the string appeared.
25	Public Function Remove ( startIndex As Integer ) As String String as public function Delete (startIndex as ( integer) As String Remove all characters from the current instance, start at the specified location, continue to the last location, and return the string.
26	Public Function Remove ( startIndex As Integer, count As Integer ) As String Strings are deleted as a public function (startIndex as an integer as an ( integer count) As String Remove the specified number of characters from the current string from the specified location and return the string.
27	Public Function Replace ( oldChar As Char, newChar As Char ) As String Public function replacement (old Char for char, newchar for CHAR) As String Replace all appearances of the specified Unicode character in the current string object with the specified Unicode character and return a new string.
28	Public Function Replace ( oldValue As String, newValue As String ) As String Public function replacement (property oldValue as string, newValue as string) As String Replace all appearances of the specified string in the current string object with the specified string and return a new string.
29	Public Function Split ( ParamArray separator As Char() ) As String() Common function split (ParamArray separator as Char()) As String() Returns an array of strings that contain substrings in the current string object, separated by elements of the specified array of Unicode characters.
30	Public Function Split ( separator As Char(), count As Integer ) As String() The common function split (separator is char(), the count is integer) As String(). Returns an array of strings that contain substrings in the current string object, separated by elements of the specified array of Unicode characters. T he int parameter specifies the maximum number of substrings to return.
31	Public Function StartsWith ( value As String ) As Boolean The common function StartsWith (value as string) As Boolean Determines whether the beginning of this string instance matches the specified string.
32	Public Function ToCharArray As Char() Public function ToCharArray As CHAR() Returns an array of Unicode characters that contain all the characters in the current string object.
33	Public Function ToCharArray ( startIndex As Integer, length As Integer ) As Char() The common function ToCharArray (startIndex is an integer, length is an integer) As Char(). Returns an array of Unicode characters that contain all the characters in the current string object, starting with the specified index until the specified length.
34	Public Function ToLower As String Public function ToLower As String Returns a converted, small copy of this string.
35	Public Function ToUpper As String Public function ToUpper As String Returns a converted capital copy of this string.
36	Public Function Trim As String The common function Trim As String Remove all leading and tail space characters from the current String object.

The methods listed above are not exhaustive, please visit the MSDN library for a complete list of methods and String class constructors.

Example:

The following example illustrates some of the above methods:

Comparison string:

Module strings
   Sub Main()
      Dim str1, str2 As String
      str1 = "This is test"
      str2 = "This is text"
      If (String.Compare(str1, str2) = 0) Then
          Console.WriteLine(str1 + " and " + str2 +
                            " are equal.")
      Else
          Console.WriteLine(str1 + " and " + str2 +
                            " are not equal.")
      End If
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following results:

This is test and This is text are not equal.

A string contains a string:

Module strings
   Sub Main()
      Dim str1 As String
      str1 = "This is test"
      If (str1.Contains("test")) Then
          Console.WriteLine("The sequence 'test' was found.")
      End If
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following results:

The sequence 'test' was found.

Substrings obtained:

Module strings
   Sub Main()
      Dim str As String
      str = "Last night I dreamt of San Pedro"
      Console.WriteLine(str)
      Dim substr As String = str.Substring(23)
      Console.WriteLine(substr)
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following results:

Last night I dreamt of San Pedro
San Pedro.

Add a string:

Module strings
   Sub Main()
      Dim strarray As String() = {"Down the way where the nights are gay",
                          "And the sun shines daily on the mountain top",
                           "I took a trip on a sailing ship",
                          "And when I reached Jamaica",
                          "I made a stop"}
      Dim str As String = String.Join(vbCrLf, strarray)
      Console.WriteLine(str)
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following results:

Down the way where the nights are gay
And the sun shines daily on the mountain top
I took a trip on a sailing ship
And when I reached Jamaica
I made a stop

VB.Net - string

Table of contents

Create a string object

The property of the String class

The method of the String class

Example:

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