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/* buffer.c Reads standard input and builds a circular buffer of maxbuffer lines */
/* input line should have max length maxline and is printed only if it is not in the buffer */
/* calling arguments: maxline maxbuffer */
/* defaults: 5000 50 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAXBUFFER 5000 /*max number of lines in buffer */
char *line;
int maxline;
int Getline(void);
void notimpl(char s[]);
int
main(int argc, char *argv[])
{
extern int maxline;
extern char *line;
int i;
int bufsize;
int next;
int count, counton;
char *c;
char *buffer [MAXBUFFER];
int maxbuffer=50;
void *calloc();
maxline=5000;
/* allocate space for buffer */
if (argc >= 2 ) maxline=atoi(argv[1])+2; /* allow for \n and \0 */
if (maxline <= 2 ) notimpl("line length must be greater than zero");
if (argc >= 3 ) maxbuffer=atoi(argv[2]);
if (maxbuffer <= 0 ) notimpl("buffer length must be greater than zero");
for(i=0;i<maxbuffer;i++) buffer[i]=calloc(maxline,sizeof(char));
line=calloc(maxline,sizeof(char));
next= -1; /*next location to write in buffer*/
bufsize= -1; /*upper index of buffer size*/
count=-1; /* count lines output "begin" before "end" minus 1*/
counton=0;
while ( Getline() > 0 )
{
i=0;
if(strncmp(line,"end",3)==0) counton=0;
while ( i <= bufsize && (strcmp(line,buffer[i])) != 0 )
i++;
if ( i > bufsize ) /* write out line and put in buffer */
{
next++;
if ( next > maxbuffer-1 ) next=0;
if ( bufsize < maxbuffer-1 ) bufsize++;
c=strcpy(buffer[next],line);
printf("%s",line);
if(counton)count++;
}
if(strncmp(line,"begin",5)==0) counton=1;
}
printf("\n*Number of output lines between begin/end = %d",count);
if(count > maxbuffer )
printf("\n*Buffer size of %d lines exceeded-some duplicates may remain",maxbuffer);
else
printf("\n*All duplicates removed");
printf("\n");
return 0;
}
/* getline from KR P.32 */
int Getline(void)
{
int c,i;
extern int maxline;
extern char *line;
for (i=0;i<maxline-1
&& (c=getchar()) != EOF && c != '\n'; ++i)
line[i]=c;
if (i == maxline-1 ) {
fprintf(stderr,"\n%s ",line);
fprintf(stderr,"\nmaximum line length = %d ",maxline-2);
notimpl("maximum line length exceded");
}
if (c == '\n' ) {
line[i]=c;
++i;
}
line[i]= '\0';
return i;
}
void notimpl( char s[])
{fprintf(stderr,"\n%s\n",s);
exit(1);
}
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