Access output variable of stored procedure with Select Command in C#

Stored Procedure Creation with output variable :

alter procedure checkLoginp

(

@username varchar(50),

@Password varchar(20),

@retVal int out

)

AS

BEGIN

if EXISTS(select email_id,Password from UserCredentials where email_id=@username and Password=@Password)

BEGIN

Set @retVal=1

END

ELSE

BEGIN

set @retVal=0

END

END

Access of Output Variable in C#

using System.Data.SqlClient;

using System.Configuration;

using System.Data;

public int checkLogin(string Username, string Password)

        {

            int returnValue = -1;

            string str = ConfigurationManager.ConnectionStrings["ConnectForum"].ConnectionString;

            SqlConnection conn = new SqlConnection(str);

            if (conn.State == ConnectionState.Closed)

            {

               

                SqlCommand cmd = new SqlCommand();

                cmd.Connection = conn;

                cmd.CommandType = CommandType.StoredProcedure;

                cmd.CommandText ="checkLoginp";

                cmd.Parameters.AddWithValue("@username", Username);

                cmd.Parameters.AddWithValue("@Password", Password);

                SqlParameter param = cmd.Parameters.Add("@retVal", SqlDbType.Int);

                param.Direction = ParameterDirection.Output;

                conn.Open();

                cmd.ExecuteNonQuery();

                

                    returnValue = Convert.ToInt32(cmd.Parameters["@retVal"].Value);

              

                cmd.Dispose();

                conn.Close();

            }

            return returnValue;

        }