Question:
I have an int list and I want to save more numbers in it, but numbers that don't repeat.
How do I find if there is already a certain value in this list?
Answer:
What you're looking for is the structure called HashSet
If an element exists in the HashSet , it will not be added again. In other words, it is a "list" that does not accept duplicate values.
To find out if a value exists in the HashSet , you can call the HashSet.Contains() function:
var hashset = new HashSet<int>()
{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
bool tem_4 = hashset.Contains(4); // verdadeiro
bool tem_11 = hashset.Contains(11); // falso
//verifica se o conjunto pertence ao hashset (caso não queira procurar um a um)
bool resultado = hashset.IsSupersetOf(new []{ 4, 6, 7 }); // verdadeiro
To add or remove it will call the functions:
hashset.Add(99); // adiciona o valor 99 a "lista"
bool add99 = hashset.Add(99); // tenta adicionar novamente 99 à "lista" (retorna falso)
//Continua havendo só um 99 na lista
hashset.Remove(99); // remove o valor 99 da "lista"
And to iterate over the set you can use foreach
foreach(int valor in hashset)
{
// faz algo
}
In addition, it is also possible to convert to list and Array :
int[] array = hashset.ToArray();
List<int> lst = hashset.ToList();