C#

a b b a c
a a b b c

public class CharData
{
    public char Character { get; set; }
    public int Count { get; set; }
}

public class CharCounter : List<CharData>
{
    public CharCounter(char[] chars)
    {
        if (chars == null)
        {
            throw new ArgumentNullException("The character array parameter cannot be null.");
        }
        if (chars.Length == 0)
        {
            throw new InvalidOperationException("The character array cannot be empty.");
        }
        foreach(char ch in chars)
        {
            this.Add(ch);
        }
    }

    public void Add(char ch)
    {
        CharData cd = this.FirstOrDefault(x=>x.Character == ch);
        if (cd == null)
        {
            this.Add(new CharData(){Character = ch, Count=1});
        }
        else
        {
            cd.Count++;
        }
    }
}

CharCounter counter = new CharCounter(new char[]{'a','b','b','a','c'});
CharData unique = counter.FirstOrDefault(x=>x.Count == 1);
string msg = (unique == null) ? "No unique characters found":string.Format("First unique character is '{0}'", unique.Character);

public class CharCounter : List<CharData>

public class Move : IEquatable<Move>
{
    ...
    
    public override int GetHashCode()
    {
        // Borrowed from: https://stackoverflow.com/a/263416/124386
        // NB: Ideally, the fields should be read-only, to prevent the hash code from changing.
        unchecked
        {
            int result = 17;
            result = result * 23 + StringComparer.Ordinal.GetHashCode(displayName ?? string.Empty);
            result = result * 23 + StringComparer.Ordinal.GetHashCode(element ?? string.Empty);
            result = result * 23 + damage.GetHashCode();
            result = result * 23 + enemyDamageSubtraction.GetHashCode();
            result = result * 23 + minimumLevel.GetHashCode();
            return result;
        }
    }
    
    public override bool Equals(object obj)
    {
        return Equals(obj as Move);
    }
    
    public bool Equals(Move other)
    {
        if (ReferenceEquals(other, null)) return false;
        
        return string.Equals(displayName, other.displayName, StringComparison.Ordinal)
            && string.Equals(element, other.element, StringComparison.Ordinal)
            && damage == other.damage
            && enemyDamageSubtraction == other.enemyDamageSubtraction
            && minimumLevel == other.minimumLevel;
    }
    
    public static bool operator ==(Move left, Move right)
    {
        return Equals(left, right);
    }
    
    public static bool operator !=(Move left, Move right)
    {
        return !Equals(left, right);
    }
}

Move tempMove = new Move
{
    displayName = "...",
    element = "...",
    damage = ...,
    enemyDamageSubtraction = ...,
    minimumLevel = ...,
};

bool alreadyInList = playerMoves.Contains(tempMove);

MyOtherForm mof = new MyOtherForm();
mof.Show();

MyOtherForm mof = new MyOtherForm();
if (mof.ShowDialog() == DialogResult.OK)
   {
   ...
   }

private string[] Temperatures = { "30C", "40C", "60C", "90C" };

private int currentTemp = 0;

private void butTemp_Click(object sender, EventArgs e)
    {
    currentTemp++;
    if (currentTemp >= Temperatures.Length)
        {
        currentTemp = 0;
        }
    butTemp.Text = Temperatures[currentTemp];
    }

public static void Main(string[] args)
    {

    int ip1, ip2, ip3, ip4, res, tem2 = 0;
    ip1 = Int32.Parse(Console.ReadLine());
    ip2 = Int32.Parse(Console.ReadLine());
    ip3 = Int32.Parse(Console.ReadLine());
    ip4 = Int32.Parse(Console.ReadLine());
    res = summeet(ip1, ip2, ip3, ip4);
    Console.WriteLine(res);
    }
private static int summeet(int p1, int p2, int p3, int p4)
    {
    int a, b, c, n, tem1, tem2 = 0, i = 0, d1, d2;
    a = p1;
    b = p2;
    c = p3;
    n = p4;
    while (i > n - 3)
        {
        d1 = b - a;
        tem1 = d1 + c;
        d2 = c - b;
        tem2 = tem1 + d2;
        i++;
        tem1 = tem2;
        }
    return tem2;
    }