Compare Method (String, Int32, String, Int32, Int32, StringComparison)

String.Compare Method (String, Int32, String, Int32, Int32, StringComparison)


Compares substrings of two specified String objects using the specified rules, and returns an integer that indicates their relative position in the sort order.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

public static int Compare(
	string strA,
	int indexA,
	string strB,
	int indexB,
	int length,
	StringComparison comparisonType


Type: System.String

The first string to use in the comparison.

Type: System.Int32

The position of the substring within strA.

Type: System.String

The second string to use in the comparison.

Type: System.Int32

The position of the substring within strB.

Type: System.Int32

The maximum number of characters in the substrings to compare.

Type: System.StringComparison

One of the enumeration values that specifies the rules to use in the comparison.

Return Value

Type: System.Int32

A 32-bit signed integer that indicates the lexical relationship between the two comparands.



Less than zero

The substring in strA precedes the substring in strB in the sort order.


The substrings occur in the same position in the sort order, or the length parameter is zero.

Greater than zero

The substring in strA follllows the substring in strB in the sort order.

Exception Condition

indexA is greater than strA.Length.


indexB is greater than strB.Length.


indexA, indexB, or length is negative.


Either indexA or indexB is null, and length is greater than zero.


comparisonType is not a StringComparison value.

The substrings to compare start in strA at indexA and in strB at indexB. Both indexA and indexB are zero-based; that is, the first character in strA and strB is at position zero, not position one. The length of the first substring is equal to the length of strA minus indexA plus one. The length of the second substring is equal to the length of strB minus indexB plus one.

The number of characters to compare is the lesser of the lengths of the two substrings, and length. The indexA, indexB, and length parameters must be nonnegative.

The comparisonType parameter indicates whether the comparison should use the current or invariant culture, honor or ignore the case of the comparands, or use word (culture-sensitive) or ordinal (culture-insensitive) sort rules.

One or both comparands can be null. By definition, any string, including the empty string (""), compares greater than a null reference; and two null references compare equal to each other.

The comparison terminates when an inequality is discovered or both substrings have been compared. However, if the two strings compare equal to the end of one string, and the other string has characters remaining, the string with remaining characters is considered greater. The return value is the result of the last comparison performed.

Unexpected results can occur when comparisons are affected by culture-specific casing rules. For example, in Turkish, the following example yields the wrong results because the file system in Turkish does not use linguistic casing rules for the letter "i" in "file".

static bool IsFileURI(String path)
    return (String.Compare(path, 0, "file:", 0, 5, true) == 0);

Compare the path name to "file" using an ordinal comparison. The correct code to do this is as follows:

static bool IsFileURI(String path)
    return (String.Compare(path, 0, "file:", 0, 5, StringComparison.OrdinalIgnoreCase) == 0);

Notes to Callers:

Character sets include ignorable characters. The Compare(String, Int32, String, Int32, Int32, StringComparison) method does not consider these characters when it performs a linguistic or culture-sensitive comparison. To recognize ignorable characters in your comparison, supply a value of StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase for the comparisonType parameter.

The following example compares two substrings.

// Sample for String.Compare(String, Int32, String, Int32, Int32)
using System;

class Sample {
    public static void Main() {
//                 0123456
    String str1 = "machine";
    String str2 = "device";
    String str;
    int result;

    Console.WriteLine("str1 = '{0}', str2 = '{1}'", str1, str2);
    result = String.Compare(str1, 2, str2, 0, 2);
    str = ((result < 0) ? "less than" : ((result > 0) ? "greater than" : "equal to"));
    Console.Write("Substring '{0}' in '{1}' is ", str1.Substring(2, 2), str1);
    Console.Write("{0} ", str);
    Console.WriteLine("substring '{0}' in '{1}'.", str2.Substring(0, 2), str2);
This example produces the following results:

str1 = 'machine', str2 = 'device'
Substring 'ch' in 'machine' is less than substring 'de' in 'device'.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Return to top
© 2015 Microsoft