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So here is my array.
double[] testArray = new double[10]; // will generate a random numbers from 1-20, too lazy to write the code I want to make a search loop to check if any values are being repeated. How do I do that?
I would prefer not to use any special built-in methods since this is a small array.
987
function checkIfArrayIsUnique(myArray) { for (var i = 0; i < myArray. length; i++) { for (var j = i+1; j < myArray. length; j++) { if (myArray[i] == myArray[j]) { return true; // means there are duplicate values } } } return false; // means there are no duplicate values. }
To count total duplicate elements in given array we need two loops. Run an outer loop loop from 0 to size . Loop structure must look like for(i=0; i<size; i++) . This loop is used to select each element of array and check next subsequent elements for duplicates elements using another nested loop.
The standard way to find duplicate elements from an array is by using the HashSet data structure. If you remember, Set abstract data type doesn't allow duplicates. You can take advantage of this property to filter duplicate elements.
Step to find duplicate in String[] Array :Get length of String Arrays using length property of Arrays. Similarly get size of Set/HashSet object using size() method. Finally compare Arrays length with Set size using if-else statement.
You could do this with a little Linq:
if (testArray.Length != testArray.Distinct().Count()) { Console.WriteLine("Contains duplicates"); } The Distinct extension method removes any duplicates, and Count gets the size of the result set. If they differ at all, then there are some duplicates in the list.
Alternatively, here's more complicated query, but it may be a bit more efficient:
if (testArray.GroupBy(x => x).Any(g => g.Count() > 1)) { Console.WriteLine("Contains duplicates"); } The GroupBy method will group any identical elements together, and Any return true if any of the groups has more than one element.
Both of the above solutions work by utilizing a HashSet<T>, but you can use one directly like this:
if (!testArray.All(new HashSet<double>().Add)) { Console.WriteLine("Contains duplicates"); } Or if you prefer a solution that doesn't rely on Linq at all:
var hashSet = new HashSet<double>(); foreach(var x in testArray) { if (!hashSet.Add(x)) { Console.WriteLine("Contains duplicates"); break; } } take look at my implementation its generic and efficient
public static bool HasDuplicates<T>(IList<T> items) { Dictionary<T, bool> map = new Dictionary<T, bool>(); for (int i = 0; i < items.Count; i++) { if (map.ContainsKey(items[i])) { return true; // has duplicates } map.Add(items[i], true); } return false; // no duplicates } here are some calls
string[] strings = new[] { "1", "2", "3" }; Utility.HasDuplicates(strings)// this will return false int[] items=new []{1,2,3,1}; Utility.HasDuplicates(items)// this will return true If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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