Get an index of array and remove everything left of that index

I have an array of ints

int[] RowOfints = 1,2,3,4,5,6,7,8,9;

if i enter for example value 4 i want to remove 1,2,3 from array and return what's left. How to do th开发者_StackOverflowat?

If you don't want to use LINQ:

int[] newRowOfInts = new int[RowOfInts.Length - index];
Array.Copy(RowOfInts, index, newRowOfInts, 0, newRowOfInts.Length);

Using Skip extension in LINQ.

int[] newArray = RowOfInts.Skip(value).ToArray();

I'm interpreting your question that you want to find the index for the value 4 and then take everything starting from that index position.

var result = RowOfInts.SkipWhile(item => item != 4); // optionally, .ToArray()

result will be an IEnumerable<int> consisting of 4 .. 9. If you want a concrete array, you can use the optional ToArray() extension method as well. If no elements in the array match the given criteria, you will get a zero-length sequence.

OK, now that I understand the question better, I will post my version of the actual requirements (again perversely emphasising effeciency over readability):

private static int[] RemoveBeforeValue(int[] source, int value)
{
    if (source == null)
        return null;
    int valueIndex = 0;
    while (valueIndex < source.Length && source[valueIndex] != value)
        valueIndex++;
    if (valueIndex == 0)
        return source;
    int[] result = new int[source.Length - valueIndex];
    Array.Copy(source, valueIndex, result, 0, result.Length);
    return result;
}

OLD ANSWER

If you want to do it the hard (but efficient!) way, then you can do this (assuming you want to remove values less than the supplied value):

private static int[] RemoveValuesLessThan(int[] source, int newMinimum)
{
    if (source == null)
        return null;
    int lessThanCount = 0;
    for (int index = 0; index < source.Length; index++)
        if (source[index] < newMinimum)
            lessThanCount++;
    if (lessThanCount == 0)
        return source;
    int[] result = new int[source.Length - lessThanCount];
    int targetIndex = 0;
    for (int index = 0; index < source.Length; index++)
        if (source[index] >= newMinimum)
            result[targetIndex++] = source[index];
    return result;
}

public static void RemoveIntsBefore(int i) 
    {
        int[] RowOfints = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

        for (int k = 0; k < RowOfints.Length; k++)
        {
            if (RowOfints.ElementAt(k) < i)
            {
                RowOfints[k] = i;
            }
        }

        RowOfints = RowOfints.Distinct().ToArray();
//this part is to write it on console
            //foreach (var item in RowOfints)
            //{
            //    Console.WriteLine(item);
            //}

            //Console.ReadLine();

    }

with this one your array does not have to be sequential

public static void RemoveIntsBefore(int i) 
    {
        int[] RowOfints = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 1,2 };                     

        Console.WriteLine("OUTPUT");
        foreach (var item in Enumerable.Range(i-1, RowOfints.Length + 1 - i).ToArray())
        {
            Console.WriteLine(RowOfints[item]);
        }

        Console.ReadLine();

    }

using System.Linq; ....

int[] RowOfints = {1,2,3,4,5,6,7,8,9};
int[] Answer = RowOfints.Where(x => x != 1 && x != 2 && x != 3).ToArray()