Linq case insensitive (without toUpper or toLower)

Linq case insensitive (without toUpper or toLower)

In LINQ, performing case-insensitive comparisons without using ToUpper() or ToLower() can be achieved by using the StringComparer class with appropriate options. The StringComparer class provides predefined comparers that support case-insensitive comparisons based on the current culture or the invariant culture.

Here's how you can perform case-insensitive comparisons in LINQ using StringComparer:

using System; using System.Collections.Generic; using System.Linq; public class Program { public static void Main() { List<string> names = new List<string> { "John", "Jane", "Bob", "jane" }; // Using the default comparer based on the current culture (case-insensitive) IEnumerable<string> result1 = names.Where(name => StringComparer.CurrentCultureIgnoreCase.Equals(name, "Jane")); // Using the invariant culture comparer (case-insensitive) IEnumerable<string> result2 = names.Where(name => StringComparer.InvariantCultureIgnoreCase.Equals(name, "Jane")); // Print the results Console.WriteLine("Current Culture Comparison:"); foreach (string name in result1) { Console.WriteLine(name); } Console.WriteLine("\nInvariant Culture Comparison:"); foreach (string name in result2) { Console.WriteLine(name); } } }

In this example, we have a list of names, and we want to perform a case-insensitive comparison to find names that are equal to "Jane." We use the StringComparer.CurrentCultureIgnoreCase comparer and the StringComparer.InvariantCultureIgnoreCase comparer to achieve case-insensitive comparisons.

StringComparer.CurrentCultureIgnoreCase uses the rules of the current culture for comparison, making it suitable for user input and scenarios where culture-specific rules matter.

StringComparer.InvariantCultureIgnoreCase uses invariant culture rules, making it suitable for cases where culture-specific rules are not necessary, such as when storing or comparing data in a consistent way across different cultures.

Both comparers will yield case-insensitive results without using ToUpper() or ToLower().

Examples

  1. "LINQ Case-Insensitive Comparison using StringComparison.OrdinalIgnoreCase"

    • Description: Perform case-insensitive comparison without using ToUpper() or ToLower().
    var result = data.Where(item => string.Equals(item.Property, "SearchValue", StringComparison.OrdinalIgnoreCase)).ToList();

  2. "C# LINQ Case-Insensitive Contains"

    • Description: Use case-insensitive Contains() without converting to upper or lower case.
    var result = data.Where(item => item.Property.Contains("SearchValue", StringComparison.OrdinalIgnoreCase)).ToList();

  3. "LINQ Case-Insensitive Sorting"

    • Description: Sort a collection case-insensitively using LINQ.
    var result = data.OrderBy(item => item.Property, StringComparer.OrdinalIgnoreCase).ToList();

  4. "C# LINQ Case-Insensitive Distinct"

    • Description: Perform case-insensitive distinct operation in LINQ.
    var result = data.Distinct(StringComparer.OrdinalIgnoreCase).ToList();

  5. "LINQ Case-Insensitive Grouping"

    • Description: Group elements case-insensitively using LINQ.
    var result = data.GroupBy(item => item.Property, StringComparer.OrdinalIgnoreCase).ToList();

  6. "C# LINQ Case-Insensitive Join"

    • Description: Perform a case-insensitive join operation in LINQ.
    var result = data.Join(otherData, item => item.Property, otherItem => otherItem.Property, (item, otherItem) => item).ToList();

  7. "LINQ Case-Insensitive Comparison for Distinct Objects"

    • Description: Use Distinct() with a custom equality comparer for case-insensitive comparison.
    var result = data.Distinct(new CaseInsensitiveComparer()).ToList(); 
    public class CaseInsensitiveComparer : IEqualityComparer<string> { public bool Equals(string x, string y) { return string.Equals(x, y, StringComparison.OrdinalIgnoreCase); } public int GetHashCode(string obj) { return obj.ToLower().GetHashCode(); } }

  8. "C# LINQ Case-Insensitive Max/Min"

    • Description: Find the maximum or minimum value case-insensitively in LINQ.
    var maxItem = data.Max(item => item.Property, StringComparer.OrdinalIgnoreCase);

  9. "LINQ Case-Insensitive Comparison for Intersect"

    • Description: Use Intersect() with a custom equality comparer for case-insensitive comparison.
    var result = data.Intersect(otherData, new CaseInsensitiveComparer()).ToList();

  10. "C# LINQ Case-Insensitive Comparison for Union"

    • Description: Use Union() with a custom equality comparer for case-insensitive comparison.
    var result = data.Union(otherData, new CaseInsensitiveComparer()).ToList();

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