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How to check if array contains a duplicate number using C#?
Firstly, set an array −
int[] arr = { 87, 55, 23, 87, 45, 23, 98 };
Now declare a dictionary and loop through the array and get the count of all the elements. The value you get from the dictionary displays the occurrence of numbers −
foreach(var count in arr) { if (dict.ContainsKey(count)) dict[count]++; else dict[count] = 1; }
Let us see the complete example −
Example
using System; using System.Collections.Generic; namespace Demo { public class Program { public static void Main(string[] args) { int[] arr = { 87, 55, 23, 87, 45, 23, 98 }; var dict = new Dictionary < int, int > (); foreach(var count in arr) { if (dict.ContainsKey(count)) dict[count]++; else dict[count] = 1; } foreach(var val in dict) Console.WriteLine("{0} occurred {1} times", val.Key, val.Value); } } }
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