1*2037Swnj /* @(#)ungetc.c 4.1 (Berkeley) 12/21/80 */ 2*2037Swnj #include <stdio.h> 3*2037Swnj 4*2037Swnj ungetc(c, iop) 5*2037Swnj register FILE *iop; 6*2037Swnj { 7*2037Swnj if (c == EOF) 8*2037Swnj return(-1); 9*2037Swnj if ((iop->_flag&_IOREAD)==0 || iop->_ptr <= iop->_base) 10*2037Swnj if (iop->_ptr == iop->_base && iop->_cnt==0) 11*2037Swnj *iop->_ptr++; 12*2037Swnj else 13*2037Swnj return(-1); 14*2037Swnj iop->_cnt++; 15*2037Swnj *--iop->_ptr = c; 16*2037Swnj return(0); 17*2037Swnj } 18