Execute a database procedure with known IN OUT arguments

/*--------------------------------------------------------------------
 * Example Pro*C program to execute a database procedure with known
 * IN OUT arguments.
 *                                              Frank Naude - Sep 2000
 *--------------------------------------------------------------------
 */
#include <stdio.h>
#include <sqlca.h>
void sqlerror();
EXEC SQL BEGIN DECLARE SECTION;
char *sqlstmt = "begin :x := upper(:x); end;";
char *connstr = "scothttps://t1.daumcdn.net/cfile/blog/ORCL";
char valstr[25];
EXEC SQL END DECLARE SECTION;
void main() {
        EXEC SQL WHENEVER SQLERROR DO sqlerror();
        EXEC SQL WHENEVER SQLWARNING CONTINUE;
        EXEC SQL CONNECT :connstr;
        EXEC SQL PREPARE stmt1 FROM :sqlstmt;
        strcpy(valstr, "Hi world");
        EXEC SQL EXECUTE stmt1 USING :valstr;
        printf("Return value: %s\n", valstr);
        return;
}
void sqlerror() {
        printf("Stop Error:\t%25i\n",sqlca.sqlcode);
        return;
}