#include <stdio.h> ungetc(c, iop) register FILE *iop; { if (c == EOF) return(-1); if ((iop->_flag&_IOREAD)==0 || iop->_ptr <= iop->_base) if (iop->_ptr == iop->_base && iop->_cnt==0) iop->_ptr++; else return(-1); iop->_cnt++; if(*--iop->_ptr != c) /* sscanf buffer may be read-only */ *iop->_ptr = c; return(c); }