Convert List of object to string array C

String.Join Method

Reference

Definition

Namespace: System Assembly:System.Runtime.dll Assembly:netstandard.dll Assembly:mscorlib.dll

Important

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Concatenates the elements of a specified array or the members of a collection, using the specified separator between each element or member.

Overloads

Join(Char, Object[])	Concatenates the string representations of an array of objects, using the specified separator between each member.
Join(Char, String[])	Concatenates an array of strings, using the specified separator between each member.
Join(String, IEnumerable)	Concatenates the members of a constructed IEnumerable collection of type String, using the specified separator between each member.
Join(String, Object[])	Concatenates the elements of an object array, using the specified separator between each element.
Join(String, String[])	Concatenates all the elements of a string array, using the specified separator between each element.
Join(Char, String[], Int32, Int32)	Concatenates an array of strings, using the specified separator between each member, starting with the element in value located at the startIndex position, and concatenating up to count elements.
Join(String, String[], Int32, Int32)	Concatenates the specified elements of a string array, using the specified separator between each element.
Join(Char, IEnumerable)	Concatenates the members of a collection, using the specified separator between each member.
Join(String, IEnumerable)	Concatenates the members of a collection, using the specified separator between each member.

Join(Char, Object[])

Concatenates the string representations of an array of objects, using the specified separator between each member.

public: static System::String ^ Join(char separator, ... cli::array ^ values); public static string Join (char separator, params object?[] values); public static string Join (char separator, params object[] values); static member Join : char * obj[] -> string Public Shared Function Join (separator As Char, ParamArray values As Object()) As String

Parameters

separator Char

The character to use as a separator. separator is included in the returned string only if value has more than one element.

values Object[]

An array of objects whose string representations will be concatenated.

Returns

String

A string that consists of the elements of values delimited by the separator character.

-or-

Empty if values has zero elements.

Exceptions

ArgumentNullException

value is null.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Applies to

Join(Char, String[])

Concatenates an array of strings, using the specified separator between each member.

public: static System::String ^ Join(char separator, ... cli::array ^ value); public static string Join (char separator, params string?[] value); public static string Join (char separator, params string[] value); static member Join : char * string[] -> string Public Shared Function Join (separator As Char, ParamArray value As String()) As String

Parameters

separator Char

The character to use as a separator. separator is included in the returned string only if value has more than one element.

value String[]

An array of strings to concatenate.

Returns

String

A string that consists of the elements of value delimited by the separator character.

-or-

Empty if value has zero elements.

Exceptions

ArgumentNullException

value is null.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Applies to

Join(String, IEnumerable)

Concatenates the members of a constructed IEnumerable collection of type String, using the specified separator between each member.

public: static System::String ^ Join(System::String ^ separator, System::Collections::Generic::IEnumerable ^ values); public static string Join (string separator, System.Collections.Generic.IEnumerable values); public static string Join (string? separator, System.Collections.Generic.IEnumerable values); [System.Runtime.InteropServices.ComVisible(false)] public static string Join (string separator, System.Collections.Generic.IEnumerable values); static member Join : string * seq -> string [] static member Join : string * seq -> string Public Shared Function Join (separator As String, values As IEnumerable(Of String)) As String

Parameters

separator String

The string to use as a separator.separator is included in the returned string only if values has more than one element.

values IEnumerable

A collection that contains the strings to concatenate.

Returns

String

A string that consists of the elements of values delimited by the separator string.

-or-

Empty if values has zero elements.

Attributes

ComVisibleAttribute

Exceptions

ArgumentNullException

values is null.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Examples

The following example uses the Sieve of Eratosthenes algorithm to calculate the prime numbers that are less than or equal to 100. It assigns the result to a List object of type String, which it then passes to the Join(String, IEnumerable) method.

using System; using System.Collections.Generic; public class Example { public static void Main() { int maxPrime = 100; List primes = GetPrimes(maxPrime); Console.WriteLine("Primes less than {0}:", maxPrime); Console.WriteLine(" {0}", String.Join(" ", primes)); } private static List GetPrimes(int maxPrime) { Array values = Array.CreateInstance(typeof(int), new int[] { maxPrime - 1}, new int[] { 2 }); // Use Sieve of Eratosthenes to determine prime numbers. for (int ctr = values.GetLowerBound(0); ctr <= (int) Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))); ctr++) { if ((int) values.GetValue(ctr) == 1) continue; for (int multiplier = ctr; multiplier <= maxPrime / 2; multiplier++) if (ctr * multiplier <= maxPrime) values.SetValue(1, ctr * multiplier); } List primes = new List(); for (int ctr = values.GetLowerBound(0); ctr <= values.GetUpperBound(0); ctr++) if ((int) values.GetValue(ctr) == 0) primes.Add(ctr); return primes; } } // The example displays the following output: // Primes less than 100: // 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 Imports System.Collections.Generic Module Example Public Sub Main() Dim maxPrime As Integer = 100 Dim primes As List(Of String) = GetPrimes(maxPrime) Console.WriteLine("Primes less than {0}:", maxPrime) Console.WriteLine(" {0}", String.Join(" ", primes)) End Sub Private Function GetPrimes(maxPrime As Integer) As List(Of String) Dim values As Array = Array.CreateInstance(GetType(Integer), _ New Integer() { maxPrime - 1}, New Integer(){ 2 }) ' Use Sieve of Eratosthenes to determine prime numbers. For ctr As Integer = values.GetLowerBound(0) To _ CInt(Math.Ceiling(Math.Sqrt(values.GetUpperBound(0)))) If CInt(values.GetValue(ctr)) = 1 Then Continue For For multiplier As Integer = ctr To maxPrime \ 2 If ctr * multiplier <= maxPrime Then values.SetValue(1, ctr * multiplier) Next Next Dim primes As New List(Of String) For ctr As Integer = values.GetLowerBound(0) To values.GetUpperBound(0) If CInt(values.GetValue(ctr)) = 0 Then primes.Add(ctr.ToString()) Next Return primes End Function End Module ' The example displays the following output: ' Primes less than 100: ' 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Remarks

If separator is null, an empty string (String.Empty) is used instead. If any member of values is null, an empty string is used instead.

Join(String, IEnumerable) is a convenience method that lets you concatenate each element in an IEnumerable(Of String) collection without first converting the elements to a string array. It is particularly useful with Language-Integrated Query (LINQ) query expressions. The following example passes a List(Of String) object that contains either the uppercase or lowercase letters of the alphabet to a lambda expression that selects letters that are equal to or greater than a particular letter (which, in the example, is "M"). The IEnumerable(Of String) collection returned by the Enumerable.Where method is passed to the Join(String, IEnumerable) method to display the result as a single string.

using System; using System.Collections.Generic; using System.Linq; public class Example { public static void Main() { string output = String.Join(" ", GetAlphabet(true).Where( letter => letter.CompareTo("M") >= 0)); Console.WriteLine(output); } private static List GetAlphabet(bool upper) { List alphabet = new List(); int charValue = upper ? 65 : 97; for (int ctr = 0; ctr <= 25; ctr++) alphabet.Add(((char)(charValue + ctr)).ToString()); return alphabet; } } // The example displays the following output: // M N O P Q R S T U V W X Y Z Imports System.Collections.Generic Imports System.Linq Module modMain Public Sub Main() Dim output As String = String.Join(" ", GetAlphabet(True).Where(Function(letter) _ letter >= "M")) Console.WriteLine(output) End Sub Private Function GetAlphabet(upper As Boolean) As List(Of String) Dim alphabet As New List(Of String) Dim charValue As Integer = CInt(IIf(upper, 65, 97)) For ctr As Integer = 0 To 25 alphabet.Add(ChrW(charValue + ctr).ToString()) Next Return alphabet End Function End Module ' The example displays the following output: ' M N O P Q R S T U V W X Y Z

Applies to

Join(String, Object[])

Concatenates the elements of an object array, using the specified separator between each element.

public: static System::String ^ Join(System::String ^ separator, ... cli::array ^ values); public static string Join (string separator, params object[] values); public static string Join (string? separator, params object?[] values); [System.Runtime.InteropServices.ComVisible(false)] public static string Join (string separator, params object[] values); static member Join : string * obj[] -> string [] static member Join : string * obj[] -> string Public Shared Function Join (separator As String, ParamArray values As Object()) As String

Parameters

separator String

The string to use as a separator. separator is included in the returned string only if values has more than one element.

values Object[]

An array that contains the elements to concatenate.

Returns

String

A string that consists of the elements of values delimited by the separator string.

-or-

Empty if values has zero elements.

-or-

.NET Framework only: Empty if the first element of values is null.

Attributes

ComVisibleAttribute

Exceptions

ArgumentNullException

values is null.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Examples

The following example uses the Sieve of Eratosthenes algorithm to calculate the prime numbers that are less than or equal to 100. It assigns the result to a integer array, which it then passes to the Join(String, Object[]) method.

using System; using System.Collections.Generic; public class Example { public static void Main() { int maxPrime = 100; int[] primes = GetPrimes(maxPrime); Console.WriteLine("Primes less than {0}:", maxPrime); Console.WriteLine(" {0}", String.Join(" ", primes)); } private static int[] GetPrimes(int maxPrime) { Array values = Array.CreateInstance(typeof(int), new int[] { maxPrime - 1}, new int[] { 2 }); // Use Sieve of Eratosthenes to determine prime numbers. for (int ctr = values.GetLowerBound(0); ctr <= (int) Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))); ctr++) { if ((int) values.GetValue(ctr) == 1) continue; for (int multiplier = ctr; multiplier <= maxPrime / 2; multiplier++) if (ctr * multiplier <= maxPrime) values.SetValue(1, ctr * multiplier); } List primes = new List(); for (int ctr = values.GetLowerBound(0); ctr <= values.GetUpperBound(0); ctr++) if ((int) values.GetValue(ctr) == 0) primes.Add(ctr); return primes.ToArray(); } } // The example displays the following output: // Primes less than 100: // 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 Module Example Public Sub Main() Dim maxPrime As Integer = 100 Dim primes() As Integer = GetPrimes(maxPrime) Console.WriteLine("Primes less than {0}:", maxPrime) Console.WriteLine(" {0}", String.Join(" ", primes)) End Sub Private Function GetPrimes(maxPrime As Integer) As Integer() Dim values As Array = Array.CreateInstance(GetType(Integer), _ New Integer() { maxPrime - 1}, New Integer(){ 2 }) ' Use Sieve of Eratosthenes to determine prime numbers. For ctr As Integer = values.GetLowerBound(0) To _ CInt(Math.Ceiling(Math.Sqrt(values.GetUpperBound(0)))) If CInt(values.GetValue(ctr)) = 1 Then Continue For For multiplier As Integer = ctr To maxPrime \ 2 If ctr * multiplier <= maxPrime Then values.SetValue(1, ctr * multiplier) Next Next Dim primes As New System.Collections.Generic.List(Of Integer) For ctr As Integer = values.GetLowerBound(0) To values.GetUpperBound(0) If CInt(values.GetValue(ctr)) = 0 Then primes.Add(ctr) Next Return primes.ToArray() End Function End Module ' The example displays the following output: ' Primes less than 100: ' 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Remarks

If separator is null or if any element of values other than the first element is null, an empty string (String.Empty) is used instead. See the Notes for Callers section if the first element of values is null.

Join(String, Object[]) is a convenience method that lets you concatenate each element in an object array without explicitly converting its elements to strings. The string representation of each object in the array is derived by calling that object's ToString method.

Notes to Callers

.NET Framework only: If the first element of values is null, the Join(String, Object[]) method does not concatenate the elements in values but instead returns Empty. A number of workarounds for this issue are available. The easiest is to assign a value of Empty to the first element of the array, as the following example shows.

object[] values = { null, "Cobb", 4189, 11434, .366 }; if (values[0] == null) values[0] = String.Empty; Console.WriteLine(String.Join("|", values)); // The example displays the following output: // |Cobb|4189|11434|0.366 Dim values() As Object = { Nothing, "Cobb", 4189, 11434, .366 } If values(0) Is Nothing Then values(0) = String.Empty Console.WriteLine(String.Join("|", values)) ' The example displays the following output: ' |Cobb|4189|11434|0.366

Applies to

Join(String, String[])

Concatenates all the elements of a string array, using the specified separator between each element.

public: static System::String ^ Join(System::String ^ separator, ... cli::array ^ value); public: static System::String ^ Join(System::String ^ separator, cli::array ^ value); public static string Join (string separator, params string[] value); public static string Join (string? separator, params string?[] value); public static string Join (string separator, string[] value); static member Join : string * string[] -> string Public Shared Function Join (separator As String, ParamArray value As String()) As String Public Shared Function Join (separator As String, value As String()) As String

Parameters

separator String

The string to use as a separator. separator is included in the returned string only if value has more than one element.

value String[]

An array that contains the elements to concatenate.

Returns

String

A string that consists of the elements in value delimited by the separator string.

-or-

Empty if values has zero elements.

Exceptions

ArgumentNullException

value is null.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Examples

The following example demonstrates the Join method.

using namespace System; String^ MakeLine( int initVal, int multVal, String^ sep ) { array^sArr = gcnew array(10); for ( int i = initVal; i < initVal + 10; i++ ) sArr[ i - initVal ] = String::Format( "{0, -3}", i * multVal ); return String::Join( sep, sArr ); } int main() { Console::WriteLine( MakeLine( 0, 5, ", " ) ); Console::WriteLine( MakeLine( 1, 6, " " ) ); Console::WriteLine( MakeLine( 9, 9, ": " ) ); Console::WriteLine( MakeLine( 4, 7, "< " ) ); } // The example displays the following output: // 0 , 5 , 10 , 15 , 20 , 25 , 30 , 35 , 40 , 45 // 6 12 18 24 30 36 42 48 54 60 // 81 : 90 : 99 : 108: 117: 126: 135: 144: 153: 162 // 28 < 35 < 42 < 49 < 56 < 63 < 70 < 77 < 84 < 91 using System; public class JoinTest { public static void Main() { Console.WriteLine(MakeLine(0, 5, ", ")); Console.WriteLine(MakeLine(1, 6, " ")); Console.WriteLine(MakeLine(9, 9, ": ")); Console.WriteLine(MakeLine(4, 7, "< ")); } private static string MakeLine(int initVal, int multVal, string sep) { string [] sArr = new string [10]; for (int i = initVal; i < initVal + 10; i++) sArr[i - initVal] = String.Format("{0,-3}", i * multVal); return String.Join(sep, sArr); } } // The example displays the following output: // 0 , 5 , 10 , 15 , 20 , 25 , 30 , 35 , 40 , 45 // 6 12 18 24 30 36 42 48 54 60 // 81 : 90 : 99 : 108: 117: 126: 135: 144: 153: 162 // 28 < 35 < 42 < 49 < 56 < 63 < 70 < 77 < 84 < 91 Public Class JoinTest Public Shared Sub Main() Console.WriteLine(MakeLine(0, 5, ", ")) Console.WriteLine(MakeLine(1, 6, " ")) Console.WriteLine(MakeLine(9, 9, ": ")) Console.WriteLine(MakeLine(4, 7, "< ")) End Sub Private Shared Function MakeLine(initVal As Integer, multVal As Integer, sep As String) As String Dim sArr(10) As String Dim i As Integer For i = initVal To (initVal + 10) - 1 sArr((i - initVal)) = [String].Format("{0,-3}", i * multVal) Next i Return [String].Join(sep, sArr) End Function 'MakeLine End Class ' The example displays the following output: ' 0 , 5 , 10 , 15 , 20 , 25 , 30 , 35 , 40 , 45 ' 6 12 18 24 30 36 42 48 54 60 ' 81 : 90 : 99 : 108: 117: 126: 135: 144: 153: 162 ' 28 < 35 < 42 < 49 < 56 < 63 < 70 < 77 < 84 < 91

Remarks

For example, if separator is ", " and the elements of value are "apple", "orange", "grape", and "pear", Join(separator, value) returns "apple, orange, grape, pear".

If separator is null, an empty string (String.Empty) is used instead. If any element in value is null, an empty string is used instead.

Applies to

Join(Char, String[], Int32, Int32)

Concatenates an array of strings, using the specified separator between each member, starting with the element in value located at the startIndex position, and concatenating up to count elements.

public: static System::String ^ Join(char separator, cli::array ^ value, int startIndex, int count); public static string Join (char separator, string?[] value, int startIndex, int count); public static string Join (char separator, string[] value, int startIndex, int count); static member Join : char * string[] * int * int -> string Public Shared Function Join (separator As Char, value As String(), startIndex As Integer, count As Integer) As String

Parameters

separator Char

Concatenates an array of strings, using the specified separator between each member, starting with the element located at the specified index and including a specified number of elements.

value String[]

An array of strings to concatenate.

startIndex Int32

The first item in value to concatenate.

count Int32

The number of elements from value to concatenate, starting with the element in the startIndex position.

Returns

String

A string that consists of count elements of value starting at startIndex delimited by the separator character.

-or-

Empty if count is zero.

Exceptions

ArgumentNullException

value is null.

ArgumentOutOfRangeException

startIndex or count are negative.

-or-

startIndex is greater than the length of value - count.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Applies to

Join(String, String[], Int32, Int32)

Concatenates the specified elements of a string array, using the specified separator between each element.

public: static System::String ^ Join(System::String ^ separator, cli::array ^ value, int startIndex, int count); public static string Join (string separator, string[] value, int startIndex, int count); public static string Join (string? separator, string?[] value, int startIndex, int count); static member Join : string * string[] * int * int -> string Public Shared Function Join (separator As String, value As String(), startIndex As Integer, count As Integer) As String

Parameters

separator String

The string to use as a separator. separator is included in the returned string only if value has more than one element.

value String[]

An array that contains the elements to concatenate.

startIndex Int32

The first element in value to use.

count Int32

The number of elements of value to use.

Returns

String

A string that consists of count elements of value starting at startIndex delimited by the separator character.

-or-

Empty if count is zero.

Exceptions

ArgumentNullException

value is null.

ArgumentOutOfRangeException

startIndex or count is less than 0.

-or-

startIndex plus count is greater than the number of elements in value.

OutOfMemoryException

Out of memory.

Examples

The following example concatenates two elements from an array of names of fruit.

// Sample for String::Join(String, String[], int int) using namespace System; int main() { array^val = {"apple","orange","grape","pear"}; String^ sep = ", "; String^ result; Console::WriteLine( "sep = '{0}'", sep ); Console::WriteLine( "val[] = {{'{0}' '{1}' '{2}' '{3}'}}", val[ 0 ], val[ 1 ], val[ 2 ], val[ 3 ] ); result = String::Join( sep, val, 1, 2 ); Console::WriteLine( "String::Join(sep, val, 1, 2) = '{0}'", result ); } /* This example produces the following results: sep = ', ' val[] = {'apple' 'orange' 'grape' 'pear'} String::Join(sep, val, 1, 2) = 'orange, grape' */ String[] val = {"apple", "orange", "grape", "pear"}; String sep = ", "; String result; Console.WriteLine("sep = '{0}'", sep); Console.WriteLine("val[] = {{'{0}' '{1}' '{2}' '{3}'}}", val[0], val[1], val[2], val[3]); result = String.Join(sep, val, 1, 2); Console.WriteLine("String.Join(sep, val, 1, 2) = '{0}'", result); // This example produces the following results: // sep = ', ' // val[] = {'apple' 'orange' 'grape' 'pear'} // String.Join(sep, val, 1, 2) = 'orange, grape' Class Sample Public Shared Sub Main() Dim val As [String]() = {"apple", "orange", "grape", "pear"} Dim sep As [String] = ", " Dim result As [String] Console.WriteLine("sep = '{0}'", sep) Console.WriteLine("val() = {{'{0}' '{1}' '{2}' '{3}'}}", val(0), val(1), val(2), val(3)) result = [String].Join(sep, val, 1, 2) Console.WriteLine("String.Join(sep, val, 1, 2) = '{0}'", result) End Sub End Class 'This example displays the following output: ' sep = ', ' ' val() = {'apple' 'orange' 'grape' 'pear'} ' String.Join(sep, val, 1, 2) = 'orange, grape'

Remarks

For example, if separator is ", " and the elements of value are "apple", "orange", "grape", and "pear", Join(separator, value, 1, 2) returns "orange, grape".

If separator is null, an empty string (String.Empty) is used instead. If any element in value is null, an empty string is used instead.

Applies to

Join(Char, IEnumerable)

Concatenates the members of a collection, using the specified separator between each member.

public: generic static System::String ^ Join(char separator, System::Collections::Generic::IEnumerable ^ values); public static string Join (char separator, System.Collections.Generic.IEnumerable values); static member Join : char * seq<'T> -> string Public Shared Function Join(Of T) (separator As Char, values As IEnumerable(Of T)) As String

Type Parameters

The type of the members of values.

Parameters

separator Char

The character to use as a separator. separator is included in the returned string only if values has more than one element.

values IEnumerable

A collection that contains the objects to concatenate.

Returns

String

A string that consists of the members of values delimited by the separator character.

-or-

Empty if values has no elements.

Exceptions

ArgumentNullException

values is null.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Applies to

Join(String, IEnumerable)

Concatenates the members of a collection, using the specified separator between each member.

public: generic static System::String ^ Join(System::String ^ separator, System::Collections::Generic::IEnumerable ^ values); public static string Join (string separator, System.Collections.Generic.IEnumerable values); public static string Join (string? separator, System.Collections.Generic.IEnumerable values); [System.Runtime.InteropServices.ComVisible(false)] public static string Join (string separator, System.Collections.Generic.IEnumerable values); static member Join : string * seq<'T> -> string [] static member Join : string * seq<'T> -> string Public Shared Function Join(Of T) (separator As String, values As IEnumerable(Of T)) As String

Type Parameters

The type of the members of values.

Parameters

separator String

The string to use as a separator. separator is included in the returned string only if values has more than one element.

values IEnumerable

A collection that contains the objects to concatenate.

Returns

String

A string that consists of the elements of values delimited by the separator string.

-or-

Empty if values has no elements.

Attributes

ComVisibleAttribute

Exceptions

ArgumentNullException

values is null.

OutOfMemoryException

The length of the resulting string overflows the maximum allowed length (MaxValue).

Examples

The following example uses the Sieve of Eratosthenes algorithm to calculate the prime numbers that are less than or equal to 100. It assigns the result to a List object of type integer, which it then passes to the Join(String, IEnumerable) method.

using System; using System.Collections.Generic; public class Example { public static void Main() { int maxPrime = 100; List primes = GetPrimes(maxPrime); Console.WriteLine("Primes less than {0}:", maxPrime); Console.WriteLine(" {0}", String.Join(" ", primes)); } private static List GetPrimes(int maxPrime) { Array values = Array.CreateInstance(typeof(int), new int[] { maxPrime - 1}, new int[] { 2 }); // Use Sieve of Eratosthenes to determine prime numbers. for (int ctr = values.GetLowerBound(0); ctr <= (int) Math.Ceiling(Math.Sqrt(values.GetUpperBound(0))); ctr++) { if ((int) values.GetValue(ctr) == 1) continue; for (int multiplier = ctr; multiplier <= maxPrime / 2; multiplier++) if (ctr * multiplier <= maxPrime) values.SetValue(1, ctr * multiplier); } List primes = new List(); for (int ctr = values.GetLowerBound(0); ctr <= values.GetUpperBound(0); ctr++) if ((int) values.GetValue(ctr) == 0) primes.Add(ctr); return primes; } } // The example displays the following output: // Primes less than 100: // 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 Imports System.Collections.Generic Module Example Public Sub Main() Dim maxPrime As Integer = 100 Dim primes As List(Of Integer) = GetPrimes(maxPrime) Console.WriteLine("Primes less than {0}:", maxPrime) Console.WriteLine(" {0}", String.Join(" ", primes)) End Sub Private Function GetPrimes(maxPrime As Integer) As List(Of Integer) Dim values As Array = Array.CreateInstance(GetType(Integer), _ New Integer() { maxPrime - 1}, New Integer(){ 2 }) ' Use Sieve of Eratosthenes to determine prime numbers. For ctr As Integer = values.GetLowerBound(0) To _ CInt(Math.Ceiling(Math.Sqrt(values.GetUpperBound(0)))) If CInt(values.GetValue(ctr)) = 1 Then Continue For For multiplier As Integer = ctr To maxPrime \ 2 If ctr * multiplier <= maxPrime Then values.SetValue(1, ctr * multiplier) Next Next Dim primes As New System.Collections.Generic.List(Of Integer) For ctr As Integer = values.GetLowerBound(0) To values.GetUpperBound(0) If CInt(values.GetValue(ctr)) = 0 Then primes.Add(ctr) Next Return primes End Function End Module ' The example displays the following output: ' Primes less than 100: ' 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Remarks

If separator is null, an empty string (String.Empty) is used instead. If any member of values is null, an empty string is used instead.

Join(String, IEnumerable) is a convenience method that lets you concatenate each member of an IEnumerable collection without first converting them to strings. The string representation of each object in the IEnumerable collection is derived by calling that object's ToString method.

This method is particular useful with Language-Integrated Query (LINQ) query expressions. For example, the following code defines a very simple Animal class that contains the name of an animal and the order to which it belongs. It then defines a List object that contains a number of Animal objects. The Enumerable.Where extension method is called to extract the Animal objects whose Order property equals "Rodent". The result is passed to the Join(String, IEnumerable) method.

using System; using System.Collections.Generic; using System.Linq; public class Animal { public string Kind; public string Order; public Animal(string kind, string order) { this.Kind = kind; this.Order = order; } public override string ToString() { return this.Kind; } } public class Example { public static void Main() { List animals = new List(); animals.Add(new Animal("Squirrel", "Rodent")); animals.Add(new Animal("Gray Wolf", "Carnivora")); animals.Add(new Animal("Capybara", "Rodent")); string output = String.Join(" ", animals.Where( animal => (animal.Order == "Rodent"))); Console.WriteLine(output); } } // The example displays the following output: // Squirrel Capybara Imports System.Collections.Generic Public Class Animal Public Kind As String Public Order As String Public Sub New(kind As String, order As String) Me.Kind = kind Me.Order = order End Sub Public Overrides Function ToString() As String Return Me.Kind End Function End Class Module Example Public Sub Main() Dim animals As New List(Of Animal) animals.Add(New Animal("Squirrel", "Rodent")) animals.Add(New Animal("Gray Wolf", "Carnivora")) animals.Add(New Animal("Capybara", "Rodent")) Dim output As String = String.Join(" ", animals.Where(Function(animal) _ animal.Order = "Rodent")) Console.WriteLine(output) End Sub End Module ' The example displays the following output: ' Squirrel Capybara

Applies to

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String.Join Method

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Definition

In this article

Overloads

Join(Char, Object[])

Parameters

Returns

Exceptions

Applies to

Join(Char, String[])

Parameters

Returns

Exceptions

Applies to

Join(String, IEnumerable)

Parameters

Returns

Exceptions

Examples

Remarks

See also

Applies to

Join(String, Object[])

Parameters

Returns

Exceptions

Examples

Remarks

Notes to Callers

See also

Applies to

Join(String, String[])

Parameters

Returns

Exceptions

Examples

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See also

Applies to

Join(Char, String[], Int32, Int32)

Parameters

Returns

Exceptions

Applies to

Join(String, String[], Int32, Int32)

Parameters

Returns

Exceptions

Examples

Remarks

See also

Applies to

Join(Char, IEnumerable)

Type Parameters

Parameters

Returns

Exceptions

Applies to

Join(String, IEnumerable)

Type Parameters

Parameters

Returns

Exceptions

Examples

Remarks

See also

Applies to

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