How to Use the User Web Service to Display the UserId using C#

Hi,

May I request for help on how should I code in C# a call on User web service which should return the userId of the logged-in user.

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        private String getLoggedInUserCredentials()
        {
            String userid = "";
            String userSignInId = txtUsername.ToString().Substring(36).Trim().ToUpper();
            int intCtrUser = 0;

            try
            {
                WSOD_User.User prxySrvcUser = new WSOD_User.User();
                WSOD_User.UserQueryPage_Input inputUser = new WSOD_User.UserQueryPage_Input();
                WSOD_User.UserQueryPage_Output outputUser = new WSOD_User.UserQueryPage_Output();

                inputUser.ListOfUser = new WSOD_User.ListOfUserQuery();
                inputUser.ListOfUser.User = new WSOD_User.UserQuery();
                inputUser.ListOfUser.User.UserSignInId = new WSOD_User.queryType();
                inputUser.ListOfUser.User.Status = new WSOD_User.queryType();