/* @(#)ungetc.c 2.1 SCCS id keyword */ #include <stdio.h> ungetc(c, iop) register FILE *iop; { if (c == EOF) return(EOF); if ((iop->_flag&_IOREAD)==0 || iop->_ptr <= iop->_base) if (iop->_ptr == iop->_base && iop->_cnt==0) *iop->_ptr++; else return(EOF); iop->_cnt++; *--iop->_ptr = c; return(c); }