Logical Question in Interview for beginner

Reverse a string without any use of predefined function

public static void Main()
{
   int n = 0;
   Console.WriteLine("Enter a string");
   string s = Console.ReadLine();
   string rev = "";
   foreach (char c in s)
   {
      n++;
   }
   while (n > 0)
   {
      rev = rev + s[n - 1];
      n = n - 1;
   }
   Console.WriteLine(rev);
   Console.ReadKey();

}

Output



Find out Second smallest number

int[] n = new int[5];
Console.WriteLine("Enter 5 number");
for (int p = 0; p < 5; p++)
{
   n[p] = Convert.ToInt32(Console.ReadLine());
}

int com = n[0];

//sorting in ascending
int temp = 0;
for (int i = 0; i < 5; i++)
{
   for (int j = i + 1; j < 5; j++)
   {
      if (n[i] > n[j])
      {
         temp = n[i];
         n[i] = n[j];
         n[j] = temp;
      }
   }
}

Console.WriteLine("Second Smallest Number is " + n[1]);

Console.ReadKey();

Output 



Find the length of string without any use of predefined function

string s;
int c = 0;
int noofA = 0;
Console.Write("Enter the string: ");
s = Console.ReadLine();

foreach (char p in s)
{
   c++;
}

Console.WriteLine("Totol Length is " +c);
Console.ReadKey();

Output 



Print Pyramid Triangles

for (int p = 1; p <= 5; p++)
{
   for (int i = p; i <= 4; i++)
   {
      Console.Write(" ");
   }
   for (int j = 1; j <= p; j++)
   {
      Console.Write(" "+p);
   }
   for (int k = p - 4; k > 1; k--)
   {
      Console.Write(" "+p);
   }
   Console.WriteLine("");
}

Console.ReadKey();

Output 



If this helps any one I feel pleasure.