String.Contains Method
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Contains(String, StringComparison) |
Returns a value indicating whether a specified string occurs within this string, using the specified comparison rules. |
Contains(Char, StringComparison) |
Returns a value indicating whether a specified character occurs within this string, using the specified comparison rules. |
Contains(Char) |
Returns a value indicating whether a specified character occurs within this string. |
Contains(String) |
Returns a value indicating whether a specified substring occurs within this string. |
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
Returns a value indicating whether a specified string occurs within this string, using the specified comparison rules.
public:
bool Contains(System::String ^ value, StringComparison comparisonType);
public bool Contains (string value, StringComparison comparisonType);
member this.Contains : string * StringComparison -> bool
Public Function Contains (value As String, comparisonType As StringComparison) As Boolean
Parameters
- value
- String
The string to seek.
- comparisonType
- StringComparison
One of the enumeration values that specifies the rules to use in the comparison.
Returns
true
if the value
parameter occurs within this string, or if value
is the empty string (""); otherwise, false
.
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Standard | 2.1 |
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
Returns a value indicating whether a specified character occurs within this string, using the specified comparison rules.
public:
bool Contains(char value, StringComparison comparisonType);
public bool Contains (char value, StringComparison comparisonType);
member this.Contains : char * StringComparison -> bool
Public Function Contains (value As Char, comparisonType As StringComparison) As Boolean
Parameters
- value
- Char
The character to seek.
- comparisonType
- StringComparison
One of the enumeration values that specifies the rules to use in the comparison.
Returns
true
if the value
parameter occurs within this string; otherwise, false
.
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Standard | 2.1 |
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
Returns a value indicating whether a specified character occurs within this string.
public:
bool Contains(char value);
public bool Contains (char value);
member this.Contains : char -> bool
Public Function Contains (value As Char) As Boolean
Parameters
- value
- Char
The character to seek.
Returns
true
if the value
parameter occurs within this string; otherwise, false
.
Remarks
This method performs an ordinal (case-sensitive and culture-insensitive) comparison.
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Standard | 2.1 |
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
- Source:
- String.Searching.cs
Returns a value indicating whether a specified substring occurs within this string.
public:
bool Contains(System::String ^ value);
public bool Contains (string value);
member this.Contains : string -> bool
Public Function Contains (value As String) As Boolean
Parameters
- value
- String
The string to seek.
Returns
true
if the value
parameter occurs within this string, or if value
is the empty string (""); otherwise, false
.
Exceptions
value
is null
.
Examples
The following example determines whether the string "fox" is a substring of a familiar quotation. If "fox" is found in the string, it also displays its starting position.
using namespace System;
int main()
{
String^ s1 = "The quick brown fox jumps over the lazy dog";
String^ s2 = "fox";
bool b = s1->Contains( s2 );
Console::WriteLine( "Is the string, s2, in the string, s1?: {0}", b );
if (b) {
int index = s1->IndexOf(s2);
if (index >= 0)
Console::WriteLine("'{0} begins at character position {1}",
s2, index + 1);
}
}
// This example displays the following output:
// 'fox' is in the string 'The quick brown fox jumps over the lazy dog': True
// 'fox begins at character position 17
string s1 = "The quick brown fox jumps over the lazy dog";
string s2 = "fox";
bool b = s1.Contains(s2);
Console.WriteLine("'{0}' is in the string '{1}': {2}",
s2, s1, b);
if (b) {
int index = s1.IndexOf(s2);
if (index >= 0)
Console.WriteLine("'{0} begins at character position {1}",
s2, index + 1);
}
// This example displays the following output:
// 'fox' is in the string 'The quick brown fox jumps over the lazy dog': True
// 'fox begins at character position 17
let s1 = "The quick brown fox jumps over the lazy dog"
let s2 = "fox"
let b = s1.Contains s2
printfn $"'{s2}' is in the string '{s1}': {b}"
if b then
let index = s1.IndexOf s2
if index >= 0 then
printfn $"'{s2} begins at character position {index + 1}"
// This example displays the following output:
// 'fox' is in the string 'The quick brown fox jumps over the lazy dog': True
// 'fox begins at character position 17
Class Example
Public Shared Sub Main()
Dim s1 As String = "The quick brown fox jumps over the lazy dog"
Dim s2 As String = "fox"
Dim b As Boolean = s1.Contains(s2)
Console.WriteLine("'{0}' is in the string '{1}': {2}",
s2, s1, b)
If b Then
Dim index As Integer = s1.IndexOf(s2)
If index >= 0 Then
Console.WriteLine("'{0} begins at character position {1}",
s2, index + 1)
End If
End If
End Sub
End Class
'
' This example displays the following output:
' 'fox' is in the string 'The quick brown fox jumps over the lazy dog': True
' 'fox begins at character position 17
Remarks
This method performs an ordinal (case-sensitive and culture-insensitive) comparison. The search begins at the first character position of this string and continues through the last character position.
To perform a culture-sensitive or ordinal case-insensitive comparison:
On .NET Core 2.1 and later versions: Call the Contains(String, StringComparison) overload instead.
On .NET Framework: Create a custom method. The following example illustrates one such approach. It defines a String extension method that includes a StringComparison parameter and indicates whether a string contains a substring when using the specified form of string comparison.
using System;
public static class StringExtensions
{
public static bool Contains(this String str, String substring,
StringComparison comp)
{
if (substring == null)
throw new ArgumentNullException("substring",
"substring cannot be null.");
else if (! Enum.IsDefined(typeof(StringComparison), comp))
throw new ArgumentException("comp is not a member of StringComparison",
"comp");
return str.IndexOf(substring, comp) >= 0;
}
}
open System
open System.Runtime.CompilerServices
[<Extension>]
type StringExtensions =
[<Extension>]
static member Contains(str: string, substring, comp: StringComparison) =
if substring = null then
invalidArg "substring" "substring cannot be null"
if Enum.IsDefined(typeof<StringComparison>, comp) |> not then
invalidArg "comp" "comp is not a member of StringComparison"
str.IndexOf(substring, comp) >= 0
String s = "This is a string.";
String sub1 = "this";
Console.WriteLine("Does '{0}' contain '{1}'?", s, sub1);
StringComparison comp = StringComparison.Ordinal;
Console.WriteLine(" {0:G}: {1}", comp, s.Contains(sub1, comp));
comp = StringComparison.OrdinalIgnoreCase;
Console.WriteLine(" {0:G}: {1}", comp, s.Contains(sub1, comp));
// The example displays the following output:
// Does 'This is a string.' contain 'this'?
// Ordinal: False
// OrdinalIgnoreCase: True
let s = "This is a string."
let sub1 = "this"
printfn $"Does '{s}' contain '{sub1}'?"
let comp = StringComparison.Ordinal
printfn $" {comp:G}: {s.Contains(sub1, comp)}"
let comp2 = StringComparison.OrdinalIgnoreCase
printfn $" {comp2:G}: {s.Contains(sub1, comp2)}"
// The example displays the following output:
// Does 'This is a string.' contain 'this'?
// Ordinal: False
// OrdinalIgnoreCase: True
Imports System.Runtime.CompilerServices
Module StringExtensions
<Extension()>
Public Function Contains(str As String, substring As String,
comp As StringComparison) As Boolean
If substring Is Nothing Then
Throw New ArgumentNullException("substring",
"substring cannot be null.")
Else If Not [Enum].IsDefined(GetType(StringComparison), comp)
Throw New ArgumentException("comp is not a member of StringComparison",
"comp")
End If
Return str.IndexOf(substring, comp) >= 0
End Function
End Module
Public Module Example
Public Sub Main
Dim s As String = "This is a string."
Dim sub1 As String = "this"
Console.WriteLine("Does '{0}' contain '{1}'?", s, sub1)
Dim comp As StringComparison = StringComparison.Ordinal
Console.WriteLine(" {0:G}: {1}", comp, s.Contains(sub1, comp))
comp = StringComparison.OrdinalIgnoreCase
Console.WriteLine(" {0:G}: {1}", comp, s.Contains(sub1, comp))
End Sub
End Module
' The example displays the following output:
' Does 'This is a string.' contain 'this'?
' Ordinal: False
' OrdinalIgnoreCase: True
If you are interested in the position of the substring value
in the current instance, you can call the IndexOf method to get the starting position of its first occurrence, or you can call the LastIndexOf method to get the starting position of its last occurrence. The example includes a call to the IndexOf(String) method if a substring is found in a string instance.
See also
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1 |
UWP | 10.0 |
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