When the string pointer is used as the output, the pointer must be initialized and its value must not be null. Sample statement:
char * p1 ;
char * p2;
p1=(char *) malloc(11);
p2=(char*) malloc(11);
strcpy(p1," ");
strcpy(p2,"00000");
EXEC SQL SELECT c1,c2 into :p1,:p2 from t1 where rownum < 2;