What's the Most Efficient Way to Perform Case-Insensitive String Comparison in C#?

Efficient String Comparison in C#

When comparing strings, it's often necessary to ignore case differences. Two common approaches are using Equals() with StringComparison.InvariantCultureIgnoreCase or converting both strings to lowercase before comparison.

Option 1: Equals() with StringComparison.InvariantCultureIgnoreCase

if (val.Equals("astringvalue", StringComparison.InvariantCultureIgnoreCase))

This option uses ordinal comparison, which is considered more efficient than culture-aware comparisons. It's recommended when speed is crucial.

Option 2: Convert to Lowercase

if (val.ToLowerCase() == "astringvalue")

Converting to lowercase before comparison can be faster if you're performing many comparisons against the same string. This is because the lowercase string is stored in memory, eliminating the need for repetitive conversions.

Optimal Solution

The most efficient choice depends on the specific scenario. For general use, it's recommended to use string.Equals() with StringComparison.OrdinalIgnoreCase.

if (string.Equals(val, "astringvalue", StringComparison.OrdinalIgnoreCase))

However, if you're comparing against a constant string multiple times, converting to lowercase may provide better performance.

Note: Remember to measure and profile your code to determine the most appropriate approach for your specific application.

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