Which methods are used to extract the characters from String?

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String.Substring Method
In this article
Substring(Int32)
Substring(Int32, Int32)
How do I extract a character from a string in Java?
Which function is needed to extract a character from a string in Java?
What are the methods of strings?
What are the string 5 methods?
What is string extraction in Java?

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String.Substring Method

Reference

Definition

Retrieves a substring from this instance.

This member is overloaded. For complete information about this member, including syntax, usage, and examples, click a name in the overload list.

Overloads

Substring(Int32)	Retrieves a substring from this instance. The substring starts at a specified character position and continues to the end of the string.
Substring(Int32, Int32)	Retrieves a substring from this instance. The substring starts at a specified character position and has a specified length.

Substring(Int32)

Retrieves a substring from this instance. The substring starts at a specified character position and continues to the end of the string.

public: System::String ^ Substring(int startIndex);public string Substring (int startIndex);member this.Substring : int -> stringPublic Function Substring (startIndex As Integer) As String

Parameters

startIndex Int32

The zero-based starting character position of a substring in this instance.

Returns

String

A string that is equivalent to the substring that begins at startIndex in this instance, or Empty if startIndex is equal to the length of this instance.

Exceptions

startIndex is less than zero or greater than the length of this instance.

Examples

The following example demonstrates obtaining a substring from a string.

using namespace System; using namespace System::Collections; int main() { array^info = { "Name: Felica Walker", "Title: Mz.", "Age: 47", "Location: Paris", "Gender: F"}; int found = 0; Console::WriteLine("The initial values in the array are:"); for each (String^ s in info) Console::WriteLine(s); Console::WriteLine("\nWe want to retrieve only the key information. That is:"); for each (String^ s in info) { found = s->IndexOf(": "); Console::WriteLine(" {0}", s->Substring(found + 2)); } } // The example displays the following output: // The initial values in the array are: // Name: Felica Walker // Title: Mz. // Age: 47 // Location: Paris // Gender: F // // We want to retrieve only the key information. That is: // Felica Walker // Mz. // 47 // Paris // F string [] info = { "Name: Felica Walker", "Title: Mz.", "Age: 47", "Location: Paris", "Gender: F"}; int found = 0; Console.WriteLine("The initial values in the array are:"); foreach (string s in info) Console.WriteLine(s); Console.WriteLine("\nWe want to retrieve only the key information. That is:"); foreach (string s in info) { found = s.IndexOf(": "); Console.WriteLine(" {0}", s.Substring(found + 2)); } // The example displays the following output: // The initial values in the array are: // Name: Felica Walker // Title: Mz. // Age: 47 // Location: Paris // Gender: F // // We want to retrieve only the key information. That is: // Felica Walker // Mz. // 47 // Paris // F let info = [| "Name: Felica Walker"; "Title: Mz." "Age: 47"; "Location: Paris"; "Gender: F" |] printfn "The initial values in the array are:" for s in info do printfn $"{s}" printfn "\nWe want to retrieve only the key information. That is:" for s in info do let found = s.IndexOf ": " printfn $" {s.Substring(found + 2)}" // The example displays the following output: // The initial values in the array are: // Name: Felica Walker // Title: Mz. // Age: 47 // Location: Paris // Gender: F // // We want to retrieve only the key information. That is: // Felica Walker // Mz. // 47 // Paris // F Public Class SubStringTest Public Shared Sub Main() Dim info As String() = { "Name: Felica Walker", "Title: Mz.", "Age: 47", "Location: Paris", "Gender: F"} Dim found As Integer = 0 Console.WriteLine("The initial values in the array are:") For Each s As String In info Console.WriteLine(s) Next s Console.WriteLine(vbCrLf + "We want to retrieve only the key information. That is:") For Each s As String In info found = s.IndexOf(": ") Console.WriteLine(" {0}", s.Substring(found + 2)) Next s End Sub End Class ' The example displays the following output: ' The initial values in the array are: ' Name: Felica Walker ' Title: Mz. ' Age: 47 ' Location: Paris ' Gender: F ' ' We want to retrieve only the key information. That is: ' Felica Walker ' Mz. ' 47 ' Paris ' F

The following example uses the Substring method to separate key/value pairs that are delimited by an equals ("=") character.

String[] pairs = { "Color1=red", "Color2=green", "Color3=blue", "Title=Code Repository" }; foreach (var pair in pairs) { int position = pair.IndexOf("="); if (position < 0) continue; Console.WriteLine("Key: {0}, Value: '{1}'", pair.Substring(0, position), pair.Substring(position + 1)); } // The example displays the following output: // Key: Color1, Value: 'red' // Key: Color2, Value: 'green' // Key: Color3, Value: 'blue' // Key: Title, Value: 'Code Repository' let pairs = [| "Color1=red"; "Color2=green"; "Color3=blue" "Title=Code Repository" |] for pair in pairs do let position = pair.IndexOf "=" if position >= 0 then printfn $"Key: {pair.Substring(0, position)}, Value: '{pair.Substring(position + 1)}'" // The example displays the following output: // Key: Color1, Value: 'red' // Key: Color2, Value: 'green' // Key: Color3, Value: 'blue' // Key: Title, Value: 'Code Repository' Module Example Public Sub Main() Dim pairs() As String = { "Color1=red", "Color2=green", "Color3=blue", "Title=Code Repository" } For Each pair In pairs Dim position As Integer = pair.IndexOf("=") If position < 0 then Continue For Console.WriteLine("Key: {0}, Value: '{1}'", pair.Substring(0, position), pair.Substring(position + 1)) Next End Sub End Module ' The example displays the following output: ' Key: Color1, Value: 'red' ' Key: Color2, Value: 'green' ' Key: Color3, Value: 'blue' ' Key: Title, Value: 'Code Repository'

The IndexOf method is used to get the position of the equals character in the string. The call to the Substring(Int32, Int32) method extracts the key name, which starts from the first character in the string and extends for the number of characters returned by the call to the IndexOf method. The call to the Substring(Int32) method then extracts the value assigned to the key. It starts at one character position beyond the equals character and extends to the end of the string.

Remarks

You call the Substring(Int32) method to extract a substring from a string that begins at a specified character position and ends at the end of the string. The starting character position is a zero-based; in other words, the first character in the string is at index 0, not index 1. To extract a substring that begins at a specified character position and ends before the end of the string, call the Substring(Int32, Int32) method.

Note

This method does not modify the value of the current instance. Instead, it returns a new string that begins at the startIndex position in the current string.

To extract a substring that begins with a particular character or character sequence, call a method such as IndexOf or IndexOf to get the value of startIndex. The second example illustrates this; it extracts a key value that begins one character position after the "=" character.

If startIndex is equal to zero, the method returns the original string unchanged.

Applies to

Substring(Int32, Int32)

Retrieves a substring from this instance. The substring starts at a specified character position and has a specified length.

public: System::String ^ Substring(int startIndex, int length);public string Substring (int startIndex, int length);member this.Substring : int * int -> stringPublic Function Substring (startIndex As Integer, length As Integer) As String

Parameters

startIndex Int32

The zero-based starting character position of a substring in this instance.

length Int32

The number of characters in the substring.

Returns

String

A string that is equivalent to the substring of length length that begins at startIndex in this instance, or Empty if startIndex is equal to the length of this instance and length is zero.

Exceptions

startIndex plus length indicates a position not within this instance.

-or-

startIndex or length is less than zero.

Examples

The following example illustrates a simple call to the Substring(Int32, Int32) method that extracts two characters from a string starting at the sixth character position (that is, at index five).

String value = "This is a string."; int startIndex = 5; int length = 2; String substring = value.Substring(startIndex, length); Console.WriteLine(substring); // The example displays the following output: // is let value = "This is a string." let startIndex = 5 let length = 2 let substring = value.Substring(startIndex, length) printfn $"{substring}" // The example displays the following output: // is Module Example Public Sub Main() Dim value As String = "This is a string." Dim startIndex As Integer = 5 Dim length As Integer = 2 Dim substring As String = value.Substring(startIndex, length) Console.WriteLine(substring) End Sub End Module ' The example displays the following output: ' is

The following example uses the Substring(Int32, Int32) method in the following three cases to isolate substrings within a string. In two cases the substrings are used in comparisons, and in the third case an exception is thrown because invalid parameters are specified.

It extracts the single character and the third position in the string (at index 2) and compares it with a "c". This comparison returns true.
It extracts zero characters starting at the fourth position in the string (at index 3) and passes it to the IsNullOrEmpty method. This returns true because the call to the Substring method returns String.Empty.
It attempts to extract one character starting at the fourth position in the string. Because there is no character at that position, the method call throws an ArgumentOutOfRangeException exception.

string myString = "abc"; bool test1 = myString.Substring(2, 1).Equals("c"); // This is true. Console.WriteLine(test1); bool test2 = string.IsNullOrEmpty(myString.Substring(3, 0)); // This is true. Console.WriteLine(test2); try { string str3 = myString.Substring(3, 1); // This throws ArgumentOutOfRangeException. Console.WriteLine(str3); } catch (ArgumentOutOfRangeException e) { Console.WriteLine(e.Message); } // The example displays the following output: // True // True // Index and length must refer to a location within the string. // Parameter name: length let myString = "abc" let test1 = myString.Substring(2, 1).Equals "c" // This is true. printfn $"{test1}" let test2 = String.IsNullOrEmpty(myString.Substring(3, 0)) // This is true. printfn $"{test2}" try let str3 = myString.Substring(3, 1) // This throws ArgumentOutOfRangeException. printfn $"{str3}" with :? ArgumentOutOfRangeException as e -> printfn $"{e.Message}" // The example displays the following output: // True // True // Index and length must refer to a location within the string. // Parameter name: length Public Class Sample Public Shared Sub Main() Dim myString As String = "abc" Dim test1 As Boolean = myString.Substring(2, 1).Equals("c") ' This is true. Console.WriteLine(test1) Dim test2 As Boolean = String.IsNullOrEmpty(myString.Substring(3, 0)) ' This is true. Console.WriteLine(test2) Try Dim str3 As String = myString.Substring(3, 1) ' This throws ArgumentOutOfRangeException. Console.WriteLine(str3) Catch e As ArgumentOutOfRangeException Console.WriteLIne(e.Message) End Try End Sub End Class ' The example displays the following output: ' True ' True ' Index and length must refer to a location within the string. ' Parameter name: length

The following example uses the Substring method to separate key/value pairs that are delimited by an equals ("=") character.

Remarks

You call the Substring(Int32, Int32) method to extract a substring from a string that begins at a specified character position and ends before the end of the string. The starting character position is a zero-based; in other words, the first character in the string is at index 0, not index 1. To extract a substring that begins at a specified character position and continues to the end of the string, call the Substring(Int32) method.

Note

This method does not modify the value of the current instance. Instead, it returns a new string with length characters starting from the startIndex position in the current string.

The length parameter represents the total number of characters to extract from the current string instance. This includes the starting character found at index startIndex. In other words, the Substring method attempts to extract characters from index startIndex to index startIndex + length - 1.

To extract a substring that begins with a particular character or character sequence, call a method such as IndexOf or LastIndexOf to get the value of startIndex.

If the substring extends from startIndex to a specified character sequence, you can call a method such as IndexOf or LastIndexOf to get the index of the ending character or character sequence. You can then convert that value to an index position in the string as follows:

If you've searched for a single character that is to mark the end of the substring, the length parameter equals endIndex - startIndex + 1, where endIndex is the return value of the IndexOf or IndexOf method. The following example extracts a continuous block of "b" characters from a string.
String s = "aaaaabbbcccccccdd"; Char charRange = 'b'; int startIndex = s.IndexOf(charRange); int endIndex = s.LastIndexOf(charRange); int length = endIndex - startIndex + 1; Console.WriteLine("{0}.Substring({1}, {2}) = {3}", s, startIndex, length, s.Substring(startIndex, length)); // The example displays the following output: // aaaaabbbcccccccdd.Substring(5, 3) = bbb let s = "aaaaabbbcccccccdd" let charRange = 'b' let startIndex = s.IndexOf charRange let endIndex = s.LastIndexOf charRange let length = endIndex - startIndex + 1 printfn $"{s}.Substring({startIndex}, {length}) = {s.Substring(startIndex, length)}" // The example displays the following output: // aaaaabbbcccccccdd.Substring(5, 3) = bbb Module Example Public Sub Main() Dim s As String = "aaaaabbbcccccccdd" Dim charRange As Char = "b"c Dim startIndex As Integer = s.Indexof(charRange) Dim endIndex As Integer = s.LastIndexOf(charRange) Dim length = endIndex - startIndex + 1 Console.WriteLine("{0}.Substring({1}, {2}) = {3}", s, startIndex, length, s.Substring(startIndex, length)) End Sub End Module ' The example displays the following output: ' aaaaabbbcccccccdd.Substring(5, 3) = bbb
If you've searched for multiple characters that are to mark the end of the substring, the length parameter equals endIndex + endMatchLength - startIndex, where endIndex is the return value of the IndexOf or IndexOf method, and endMatchLength is the length of the character sequence that marks the end of the substring. The following example extracts a block of text that contains an XML element.
String s = "extantstill in existence"; String searchString = ""; int startIndex = s.IndexOf(searchString); searchString = "extantstill in existence // Substring; still in existence let s = "extantstill in existence" let searchString = "" let startIndex = s.IndexOf(searchString) let searchString = "extantstill in existence // Substring; still in existence Module Example Public Sub Main() Dim s As String = "extantstill in existence" Dim searchString As String = "" Dim startindex As Integer = s.IndexOf(searchString) searchString = "extantstill in existence ' Substring; still in existence
If the character or character sequence is not included in the end of the substring, the length parameter equals endIndex - startIndex, where endIndex is the return value of the IndexOf or IndexOf method.

If startIndex is equal to zero and equals the length of the current string, the method returns the original string unchanged.

Applies to

How do I extract a character from a string in Java?

Using String..

Get the string and the index..

Create an empty char array of size 1..

Copy the element at specific index from String into the char[] using String. getChars() method..

Get the specific character at the index 0 of the character array..

Return the specific character..

Which function is needed to extract a character from a string in Java?

In Java, the charAt() function returns a character at the specified index of a string.

What are the methods of strings?

Java String Methods.

Java String split() Splits the string at the specified string (regex).

Java String compareTo() Compares two strings in the dictionary order..

Java String compareToIgnoreCase() ... .

Java String length() ... .

Java String replace() ... .

Java String replaceAll() ... .

Java String substring() ... .

Java String equals().

What are the string 5 methods?

Let's dive deep into the most commonly used Java string methods and understand their working..

indexOf() Used to find characters and substrings in a string. ... .

toCharArray() Used to form a new character array from this string. ... .

charAt() ... .

concat() ... .

replace() ... .

substring() ... .

split() ... .

compareTo().

What is string extraction in Java?

Java String class provides the built-in substring() method that extract a substring from the given string by using the index values passed as an argument. In case of substring() method startIndex is inclusive and endIndex is exclusive. Suppose the string is "computer", then the substring will be com, compu, ter, etc.

Cryto Eth

Which methods are used to extract the characters from String?

String.Substring Method

Definition

In this article

Overloads

Substring(Int32)

Parameters

Returns

Exceptions

Examples

Remarks

See also

Applies to

Substring(Int32, Int32)

Parameters

Returns

Exceptions

Examples

Remarks

See also

Applies to

How do I extract a character from a string in Java?

Which function is needed to extract a character from a string in Java?

What are the methods of strings?

What are the string 5 methods?

What is string extraction in Java?

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