What's the Best Way to Compare Strings in C#?

In-depth understanding of string comparison in C#

String comparison is a common task in C# and there are several methods to choose from. Although they look similar, subtle differences can affect the comparison.

Comparison methods

Consider the following comparison method:

• CompareTo(string otherString): Use CultureInfo.CurrentCulture.CompareInfo to perform culture-dependent comparisons.
• Equals(string otherString): Checks string equality using sequential comparison by default, but accepts the StringComparison option.
• == operator: Calls the static Equals(string a, string b) method and does not treat null values ​​as equal.

Main differences

Null value handling: Equals() will throw a null reference exception if comparing empty strings, but == will not.

Culture Dependencies: CompareTo() uses culture-specific comparison rules, which may affect results in localized environments. Equals() uses sequential comparison by default, ignoring cultural differences.

Direct comparison: The difference between the == operator and Equals() is that it compares references directly instead of checking whether the contents are equal.

Additional options: Object.ReferenceEquals(string a, string b) checks whether the references of the strings are the same, indicating that they are the same object instance.

Usage suggestions

When comparing for equality, consider the type of comparison required:

• If you need a culture-dependent comparison, use CompareTo().
• For culture-independent comparisons, use Equals() with StringComparison.Ordinal.
• For general comparisons, the == operator is usually sufficient.

Note that these methods have overloads that provide additional comparison options, such as ignoring case or diacritics.

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