String.CompareTo Method (String)
Compares this instance with a specified String object and indicates whether this instance precedes, follows, or appears in the same position in the sort order as the specified string.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- strB
-
Type:
System.String
The string to compare with this instance.
Return Value
Type: System.Int32A 32-bit signed integer that indicates whether this instance precedes, follows, or appears in the same position in the sort order as the strB parameter.
Value | Condition |
|---|---|
Less than zero | This instance precedes strB. |
Zero | This instance has the same position in the sort order as strB. |
Greater than zero | This instance follows strB. -or- strB is null. |
Implements
IComparable(Of T).CompareTo(T)This method performs a word (case-sensitive and culture-sensitive) comparison using the current culture. For more information about word, string, and ordinal sorts, see System.Globalization.CompareOptions.
Caution |
|---|
The CompareTo method was designed primarily for use in sorting or alphabetizing operations. It should not be used when the primary purpose of the method call is to determine whether two strings are equivalent. To determine whether two strings are equivalent, call the Equals method. |
For more information about the behavior of this method, see the Remarks section of the Compare(String, String) method.
This method implements the System.IComparable(Of T) interface and performs slightly better than the String.CompareTo(Object) method, because it does not have to determine whether the strB argument is a mutable value type that must be boxed, and it does not have to cast its parameter from an Objectto aString.
Notes to Callers:
Character sets include ignorable characters. The CompareTo(String) method does not consider such characters when it performs a culture-sensitive comparison. For example, if the following code is run on the .NET Framework 4 or later, a comparison of "animal" with "ani-mal" (using a soft hyphen, or U+00AD) indicates that the two strings are equivalent.
Module Example Public Sub Main() Dim s1 As String = "ani" + ChrW(&h00AD) + "mal" Dim s2 As String = "animal" Console.WriteLine("Comparison of '{0}' and '{1}': {2}", s1, s2, s1.CompareTo(s2)) End Sub End Module ' The example displays the following output: ' Comparison of 'ani-mal' and 'animal': 0
To recognize ignorable characters in a string comparison, call the CompareOrdinal(String, String) method.
The following example uses the CompareTo method to compare the current string instance with another string.
Public Module Example Public Sub Main() Dim strFirst As String = "Goodbye" Dim strSecond As String = "Hello" Dim strThird As String = "a small string" Dim strFourth As String = "goodbye" ' Compare a string to itself. Console.WriteLine(CompareStrings(strFirst, strFirst)) Console.WriteLine(CompareStrings(strFirst, strSecond)) Console.WriteLine(CompareStrings(strFirst, strThird)) ' Compare a string to another string that varies only by case. Console.WriteLine(CompareStrings(strFirst, strFourth)) Console.WriteLine(CompareStrings(strFourth, strFirst)) End Sub Private Function CompareStrings(str1 As String, str2 As String) As String Dim cmpVal As Integer = str1.CompareTo(str2) If cmpVal = 0 Then ' The values are the same. Return "The strings occur in the same position in the sort order." ElseIf cmpVal < 0 Then Return "The first string precedes the second in the sort order." Else Return "The first string follows the second in the sort order." End If End Function End Module ' This example displays the following output: ' The strings occur in the same position in the sort order. ' The strings occur in the same position in the sort order. ' The first string precedes the second in the sort order. ' The first string follows the second in the sort order. ' The first string follows the second in the sort order. ' The first string precedes the second in the sort order.
The following example demonstrates generic and non-generic versions of the CompareTo method for several value and reference types.
' This example demonstrates the generic and non-generic versions of the ' CompareTo method for several base types. ' The non-generic version takes a parameter of type Object, while the generic ' version takes a type-specific parameter, such as Boolean, Int32, or Double. Imports System Class Sample Public Shared Sub Main() Dim nl As String = Environment.NewLine Dim msg As String = _ "{0}The following is the result of using the generic and non-generic{0}" & _ "versions of the CompareTo method for several base types:{0}" Dim now As DateTime = DateTime.Now ' Time span = 11 days, 22 hours, 33 minutes, 44 seconds Dim tsX As New TimeSpan(11, 22, 33, 44) ' Version = 1.2.333.4 Dim versX As New Version("1.2.333.4") ' Guid = CA761232-ED42-11CE-BACD-00AA0057B223 Dim guidX As New Guid("{CA761232-ED42-11CE-BACD-00AA0057B223}") Dim a1 As [Boolean] = True, a2 As [Boolean] = True Dim b1 As [Byte] = 1, b2 As [Byte] = 1 Dim c1 As Int16 = -2, c2 As Int16 = 2 Dim d1 As Int32 = 3, d2 As Int32 = 3 Dim e1 As Int64 = 4, e2 As Int64 = -4 Dim f1 As [Decimal] = -5.5D, f2 As [Decimal] = 5.5D Dim g1 As [Single] = 6.6F, g2 As [Single] = 6.6F Dim h1 As [Double] = 7.7, h2 As [Double] = -7.7 Dim i1 As [Char] = "A"c, i2 As [Char] = "A"c Dim j1 As String = "abc", j2 As String = "abc" Dim k1 As DateTime = now, k2 As DateTime = now Dim l1 As TimeSpan = tsX, l2 As TimeSpan = tsX Dim m1 As Version = versX, m2 As New Version("2.0") Dim n1 As Guid = guidX, n2 As Guid = guidX ' The following types are not CLS-compliant. ' SByte, UInt16, UInt32, UInt64 Console.WriteLine(msg, nl) Try ' The second and third Show method call parameters are automatically boxed because ' the second and third Show method declaration arguments expect type Object. Show("Boolean: ", a1, a2, a1.CompareTo(a2), a1.CompareTo(CObj(a2))) Show("Byte: ", b1, b2, b1.CompareTo(b2), b1.CompareTo(CObj(b2))) Show("Int16: ", c1, c2, c1.CompareTo(c2), c1.CompareTo(CObj(c2))) Show("Int32: ", d1, d2, d1.CompareTo(d2), d1.CompareTo(CObj(d2))) Show("Int64: ", e1, e2, e1.CompareTo(e2), e1.CompareTo(CObj(e2))) Show("Decimal: ", f1, f2, f1.CompareTo(f2), f1.CompareTo(CObj(f2))) Show("Single: ", g1, g2, g1.CompareTo(g2), g1.CompareTo(CObj(g2))) Show("Double: ", h1, h2, h1.CompareTo(h2), h1.CompareTo(CObj(h2))) Show("Char: ", i1, i2, i1.CompareTo(i2), i1.CompareTo(CObj(i2))) Show("String: ", j1, j2, j1.CompareTo(j2), j1.CompareTo(CObj(j2))) Show("DateTime: ", k1, k2, k1.CompareTo(k2), k1.CompareTo(CObj(k2))) Show("TimeSpan: ", l1, l2, l1.CompareTo(l2), l1.CompareTo(CObj(l2))) Show("Version: ", m1, m2, m1.CompareTo(m2), m1.CompareTo(CObj(m2))) Show("Guid: ", n1, n2, n1.CompareTo(n2), n1.CompareTo(CObj(n2))) ' Console.WriteLine("{0}The following types are not CLS-compliant:", nl) Console.WriteLine("SByte, UInt16, UInt32, UInt64") Catch e As Exception Console.WriteLine(e) End Try End Sub 'Main Public Shared Sub Show(caption As String, var1 As [Object], var2 As [Object], _ resultGeneric As Integer, resultNonGeneric As Integer) Dim relation As String Console.Write(caption) If resultGeneric = resultNonGeneric Then If resultGeneric < 0 Then relation = "less than" ElseIf resultGeneric > 0 Then relation = "greater than" Else relation = "equal to" End If Console.WriteLine("{0} is {1} {2}", var1, relation, var2) ' The following condition will never occur because the generic and non-generic ' CompareTo methods are equivalent. Else Console.WriteLine("Generic CompareTo = {0}; non-generic CompareTo = {1}", _ resultGeneric, resultNonGeneric) End If End Sub 'Show End Class 'Sample ' 'This example produces the following results: ' 'The following is the result of using the generic and non-generic versions of the 'CompareTo method for several base types: ' 'Boolean: True is equal to True 'Byte: 1 is equal to 1 'Int16: -2 is less than 2 'Int32: 3 is equal to 3 'Int64: 4 is greater than -4 'Decimal: -5.5 is less than 5.5 'Single: 6.6 is equal to 6.6 'Double: 7.7 is greater than -7.7 'Char: A is equal to A 'String: abc is equal to abc 'DateTime: 12/1/2003 5:37:46 PM is equal to 12/1/2003 5:37:46 PM 'TimeSpan: 11.22:33:44 is equal to 11.22:33:44 'Version: 1.2.333.4 is less than 2.0 'Guid: ca761232-ed42-11ce-bacd-00aa0057b223 is equal to ca761232-ed42-11ce-bacd-00 'aa0057b223 ' 'The following types are not CLS-compliant: 'SByte, UInt16, UInt32, UInt64 '
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
