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Metodo String.Compare (String, Int32, String, Int32, Int32, Boolean)

 

Confronta le sottostringhe di due oggetti String specificati, ignorando o rispettando la distinzione tra maiuscole e minuscole, e restituisce un intero che ne indica la posizione relativa nell'ordinamento.

Spazio dei nomi:   System
Assembly:  mscorlib (in mscorlib.dll)

public static int Compare(
	string strA,
	int indexA,
	string strB,
	int indexB,
	int length,
	bool ignoreCase
)

Parametri

strA
Type: System.String

Prima stringa da usare nel confronto.

indexA
Type: System.Int32

Posizione della sottostringa all'interno di strA.

strB
Type: System.String

Seconda stringa da usare nel confronto.

indexB
Type: System.Int32

Posizione della sottostringa all'interno di strB.

length
Type: System.Int32

Numero massimo di caratteri contenuti nelle sottostringhe da confrontare.

ignoreCase
Type: System.Boolean

true per ignorare la distinzione tra maiuscole e minuscole durante il confronto; in caso contrario, false.

Valore restituito

Type: System.Int32

Intero con segno a 32 bit che indica la relazione lessicale tra i due termini di confronto.

Valore

Condizione

Minore di zero

La sottostringa in strA precede la sottostringa in strB nell'ordinamento.

Zero

Le sottostringhe si trovano nella stessa posizione nell'ordinamento oppure length è zero.

Maggiore di zero

La sottostringa in strA segue la sottostringa in strB nell'ordinamento.

Exception Condition
ArgumentOutOfRangeException

indexA è maggiore di strA.Length.

-oppure-

indexB è maggiore di strB.Length.

-oppure-

indexA, indexB o length è negativo.

-oppure-

indexA o indexB è null e length è maggiore di zero.

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. 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 comparison uses the current culture to obtain culture-specific information such as casing rules and the alphabetic order of individual characters. For example, a culture could specify that certain combinations of characters be treated as a single character, or uppercase and lowercase characters be compared in a particular way, or that the sorting order of a character depends on the characters that precede or follow it.

The comparison is performed using word sort rules. For more information about word, string, and ordinal sorts, see T:System.Globalization.CompareOptions.

System_CAPS_warningAvviso

When comparing strings, you should call the M:System.String.Compare(System.String,System.Int32,System.String,System.Int32,System.Int32,System.StringComparison) method, which requires that you explicitly specify the type of string comparison that the method uses. For more information, see Best Practices for Using Strings in the .NET Framework.

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, then 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);
}

The path name needs to be compared in an invariant manner. 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);
}

Note per i chiamanti:

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

The following example performs two comparisons of two substrings that only differ in case. The first comparison ignores case and the second comparison considers case.

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

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

    Console.WriteLine();
    Console.WriteLine("str1 = '{0}', str2 = '{1}'", str1, str2);
    Console.WriteLine("Ignore case:");
    result = String.Compare(str1, 2, str2, 2, 2, true);
    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(2, 2), str2);

    Console.WriteLine();
    Console.WriteLine("Honor case:");
    result = String.Compare(str1, 2, str2, 2, 2, false);
    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(2, 2), str2);
    }
}
/*
This example produces the following results:

str1 = 'MACHINE', str2 = 'machine'
Ignore case:
Substring 'CH' in 'MACHINE' is equal to substring 'ch' in 'machine'.

Honor case:
Substring 'CH' in 'MACHINE' is greater than substring 'ch' in 'machine'.
*/

.NET Framework
Disponibile da 1.1
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