#ifndef lintstatic char sccsid[] = "@(#)alpha.seek.c	2.3	5/27/93";#endif not lint## include "stdio.h"# include "ctype.h"# include "streams.h"# define  nexttry           ((high+low)/2)/*  alpha_seek(stream, word, s_size, fold)        seeks the first line in stream that is at least word.    assumes that stream is a sorted file of lines.  (last char must be \n)    if fold, assumes that word is lowercase and folds stream to lowercase.    s_size = size of stream    returns 1 if word = line, 0 o.w.*/int alpha_seek(stream, word, s_size, fold)FILE *stream;char *word;long int s_size;int  fold;{   long int high, low, mid;    /*  point to beginning of a line in stream  */    int      ans;               /*  line(low) < word <= line(high)          */    char     line[maxstr];    /*  initialize low (return if first line >= word)       */        low= 0L;        pos(low); getline(stream, line);        if (fold) foldline(line);        ans= strcmp(line,word);        if ( ans >= 0)        {   pos(low);   return(ans==0); }    /*  initialize high to "line" after last line           */        high= s_size;    mid= nextline(stream, nexttry );    while (mid < high )    {   getline(stream,line);        if (fold) foldline(line);        if (strcmp(line,word) < 0)    low=  mid;        else                          high= mid;        mid= nextline(stream, nexttry );    }    /* linear search from low to high   */        low= nextline(stream,low);        for(;;)        {   if (low>=high)      break;            getline(stream,line);            if (fold) foldline(line);            ans=strcmp(line,word);            if (ans>=0)         break;            low= ftell(stream);        }    pos(low);    if (low==high)  return(0);    else            return(ans==0);}/*  foldline(p):    change all uppercase to lowercase in string p*/foldline(p)char *p;{   for (; *p!=NULL;  p++)    {   if (isupper(*p))    *p = tolower(*p);    }}