1 /* ungetc.c 4.2 83/09/25 */ 2 3 #include <stdio.h> 4 5 ungetc(c, iop) 6 register FILE *iop; 7 { 8 if (c == EOF) 9 return (-1); 10 if ((iop->_flag&_IOREAD) == 0 || iop->_ptr <= iop->_base) 11 if (iop->_ptr == iop->_base && iop->_cnt == 0) 12 *iop->_ptr++; 13 else 14 return (EOF); 15 iop->_cnt++; 16 *--iop->_ptr = c; 17 return (c); 18 } 19