IndexOf<T>()
Returns the index of the first occurrence in a sequence by using the default equality comparer or a specified one.
Source
using System;
using System.Collections.Generic;
using System.Linq;
namespace ReflectionIT.Collections.Generic {
public static class Extensions {
/// <summary>
/// Returns the index of the first occurrence in a sequence by using the default equality comparer.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <param name="list">A sequence in which to locate a value.</param>
/// <param name="value">The object to locate in the sequence</param>
/// <returns>The zero-based index of the first occurrence of value within the entire sequence, if found; otherwise, –1.</returns>
public static int IndexOf<TSource>(this IEnumerable<TSource> list, TSource value) where TSource : IEquatable<TSource> {
return list.IndexOf<TSource>(value, EqualityComparer<TSource>.Default);
}
/// <summary>
/// Returns the index of the first occurrence in a sequence by using a specified IEqualityComparer.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <param name="list">A sequence in which to locate a value.</param>
/// <param name="value">The object to locate in the sequence</param>
/// <param name="comparer">An equality comparer to compare values.</param>
/// <returns>The zero-based index of the first occurrence of value within the entire sequence, if found; otherwise, –1.</returns>
public static int IndexOf<TSource>(this IEnumerable<TSource> list, TSource value, IEqualityComparer<TSource> comparer) {
int index = 0;
foreach (var item in list) {
if (comparer.Equals(item, value)) {
return index;
}
index++;
}
return -1;
}
}
}
Example
using System;
using System.Collections.Generic;
using System.Linq;
using ReflectionIT.Collections.Generic;
namespace ConsoleApplication3 {
class Program {
static void Main(string[] args) {
int[] numbers = new int[] { 5, 3, 12, 56, 43 };
int index = numbers.IndexOf(123);
Console.WriteLine(index);
}
}
}
Author: Fons Sonnemans
Submitted on: 4 mrt. 2009
Language: C#
Type: System.Collections.Generic.IEnumerable<T>
Views: 13048