[algogeeks] Re: how to implement TAIL command of unix.
read the i/p file
count the no. of '\n' characters
if count k (argument of tail) then print all chars till EOF
correct me if m wrong !!!
On Aug 16, 9:16 am, vikas kumar vikas.kumar...@gmail.com wrote:
the method of farword seek is inefficient. consider case of 10
lines and you want to display only 3-4 lines. better seek from end.
se a buffer[buf_size].
let size =filesize.
lc = 0;
while(lc = given line input)
{
fseek(fp, size);
if(size buf_size)
fread(fp, size, buffer);
else
fread(fp, size, buf_size);
parse buf_size for '\n'
if( \n is in buffer )
increment line counter(lc ++)
if(size buf_size)
size -= buf_size
}
// you know the size, read the buffer one by one and print it
OR
// you could have put them while reading on to stack and print it out
now
On Aug 15, 8:46 am, Dave dave_and_da...@juno.com wrote:
Enter the lines into a FIFO queue as you read them. After you have
enqueued n lines, dequeue a line every time you enqueue one, so that
the queue will contain the last n (or fewer) lines of the file.
Dave
On Aug 13, 1:13 pm, amit amitjaspal...@gmail.com wrote:
I am trying using fseek but somehow its not working?- Hide quoted text -
- Show quoted text -
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[algogeeks] Re: how to implement TAIL command of unix.
the method of farword seek is inefficient. consider case of 10
lines and you want to display only 3-4 lines. better seek from end.
use a buffer[buf_size].
let size =filesize.
lc = 0;
while(lc = given line input)
{
fseek(fp, size);
if(size buf_size)
fread(fp, size, buffer);
else
fread(fp, size, buf_size);
parse buf_size for '\n'
if( \n is in buffer )
increment line counter(lc ++)
if(size buf_size)
size -= buf_size
}
// you know the size, read the buffer one by one and print it
OR
// you could have put them while reading on to stack and print it out
now
On Aug 15, 8:46 am, Dave dave_and_da...@juno.com wrote:
Enter the lines into a FIFO queue as you read them. After you have
enqueued n lines, dequeue a line every time you enqueue one, so that
the queue will contain the last n (or fewer) lines of the file.
Dave
On Aug 13, 1:13 pm, amit amitjaspal...@gmail.com wrote:
I am trying using fseek but somehow its not working?- Hide quoted text -
- Show quoted text -
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[algogeeks] Re: how to implement TAIL command of unix.
Tail by default displays last 10 lines of file. 1. mmap the file 2. keep two pointers(A, B) pointing to beginning of the file 2. search for 10th \n using B, if not found i.e file has less than 10 lines, print from beginning to end 3. if found, start incrementing both A and B to the next \n. untill B reaches end of file. 4. Print from A till end of file. On 13 Aug, 23:13, amit amitjaspal...@gmail.com wrote: I am trying using fseek but somehow its not working? -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
[algogeeks] Re: how to implement TAIL command of unix.
Tail works on stdin, too. Can't mmap that. The usual way is to buffer the last N lines read in a ring buffe.r On Aug 14, 4:22 pm, Prem Mallappa prem.malla...@gmail.com wrote: Tail by default displays last 10 lines of file. 1. mmap the file 2. keep two pointers(A, B) pointing to beginning of the file 2. search for 10th \n using B, if not found i.e file has less than 10 lines, print from beginning to end 3. if found, start incrementing both A and B to the next \n. untill B reaches end of file. 4. Print from A till end of file. On 13 Aug, 23:13, amit amitjaspal...@gmail.com wrote: I am trying using fseek but somehow its not working? -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
[algogeeks] Re: how to implement TAIL command of unix.
Enter the lines into a FIFO queue as you read them. After you have enqueued n lines, dequeue a line every time you enqueue one, so that the queue will contain the last n (or fewer) lines of the file. Dave On Aug 13, 1:13 pm, amit amitjaspal...@gmail.com wrote: I am trying using fseek but somehow its not working? -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
