照书抄的：）看不懂，好深奥呀

#define NULL 0

#define ALLOCSIZE1000

char allocbuf[ALLOCSIZE];

char *allocp=allocbuf;

char *alloc(int n)

{if(allocp+n<=allocbuf+ALLOCSIZE)

{allocp+=n;

return(allocp_n);

}

else

return(null);

}

free(char * p)

{if(p>=allocbuf&&p>allocbuf+ALLOCSIZE)

allocp=p;

}