Thread: print lines

Consider taking a look at this FAQ example on how to read input. I'll assume you mean from a file you're opening, otherwise, you'll have to be a bit more clear on where the "lines" are coming from. If I'm assuming correct:

Code:

open the file
read input from user
    while the current line count is less than the starting line
        read and discard this line from the file
    while the current line count is less than the ending line
        read and display this line from the file
close the file

That should get you started. Post your code attempt, specific errors, and all the good stuff like that covered in the Announcement that covers getting help.

Quzah.

Try this

Code:

#include <stdio.h>
int main ( int argc, char *argv[] ) {
    char buff[BUFSIZ];
    int max_lines = 10000;
    while ( fgets( buff, BUFSIZ, stdin ) != NULL ) {
        int first = 1, last = max_lines;
        if ( sscanf( buff, "p %d-%d", &first, &last ) == 2 ) {
            // 2 params indicates a range
        } else if ( sscanf( buff, "p %d", &first ) == 1 ) {
            // 1 param means just that line
            last = first;
        } else if ( buff[0] == 'p' ) {
            // no params means print all
        } else {
            printf( "I don't understand %s", buff );
            continue;
        }
        printf( "printing from lines %d to %d\n", first, last );
    }
    return 0;
}

Once you have first and last, then go and print those lines using some other function

This prints all lines

Code:

while ( fgets( buff, sizeof buff, fp ) {
  fputs( buff, stdout )
}

Now you
1. add a counter which counts the lines
2. compare that counter with your limits
3. print lines which match your criteria

If you want a loop to do something, you need to do it one of two ways:

Code:

while( something_is_happening )
    do_this_one_thing( );

Or...

Code:

while( something_is_happening )
{
    do_this_thing( );
    and_this_thing( );
    ...
    and_all_these_things( );
}

Notice the difference between the first example, and your while loops. If you have a ; at the end of the line where your while loop is, it means that you're doing in effect, nothing. You either need to remove the ; at the end of your loop for it to use the next line only, or use { } around the all the lines you want it to do.

You have another problem, in that, you are not incrementing count in your first loop, so it is going to sit there indefinately.

To get in good practice, I'd suggest you use the { } on all of your loops and if else statements.

Quzah.