How to get the index of an array element

int[] Array = { 5, 8, 3, 7 };
int Element = 3;
int Index;

for (int i = 0; i < Array.Length; i++)
{
     if (Element == Array[i])
     {
         Index = i;
     }
}

List<int> index_list =new List<int>();
int srch=3;

for (int i = 0; i < Array.Length; i++)
{
     if (srch == Array[i])
     {
         index_list.Add(i);
     }
}

foreach (int index in index_list) // Loop through List with foreach
        {
            // do ur coding for index here
        }

</int></int>

public int GetIndexOfArray(string Element, string[] Array)
{
  for ( int i = 0; i < Array.Length; i++)
  {
      if( Element == Array[i])
      {
          return i;
      }
  }
return -1;
}

int x = GetIndexOfArray(Element, Array);
/*if x = -1 then there is no such Element, else it will return the index of the Element in the Array*/