int
tmpfil(struct tempblk *tb)
{
int fd;
int len;
size_t size_left = TMPOUTSZ - tmpout_offset;
/* make sure tmp file does not already exist. */
do {
len = snprintf((char *)&tmpout[tmpout_offset], size_left,
"%u", serial);
fd = open((char *)tmpout, O_RDWR|O_CREAT|O_EXCL, 0600);
serial++;
if ((serial >= UINT_MAX) || (len >= size_left)) {
/*
* We've already cycled through all the possible
* numbers or the tmp file name is being
* truncated anyway (although TMPOUTSZ should be
* big enough), so start over.
*/
serial = 0;
break;
}
} while ((fd == -1) && (errno == EEXIST));
if (fd != -1) {
pushtemp(fd, tb);
return (fd);
}
else
failed(tmpout, badcreate);
}
int main(void)
{
int c;
readline();
while ((c = get_c()) != '\n') {
switch (c){
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
unget_c();
readn();
break;
case '+': case '-': /* 遇到加减法时,先读入下一组数字,再存入运算符号 */
readn();
pushstr(c);
break;
case '*': case '/': /* 遇到乘除法时,现把当前的预算符出栈,存入操作数,再存入乘除符号 */
pushtemp(popstr());
readn();
pushstr(c);
pushstr(poptemp()); /* 原先的预算符号进栈 */
default:
break;
}
}
/* 输出逆波兰数序 */
pushstr('\0');
printf("%s\n", str);
return 0;
}
