I've got a program that reads a text file line by line (using std.stdio readln()) and I'd like to refer to the line number when I send a message to stderr upon finding a mis-formatted line.  Is there a way to get the current line number?  Of course, I could create a counter and increment it with each call to readln, but is there a "cool" way of doing this?

Okay, call me lazy... just don't call me late for dinner! :-)

Robert

On 06/04/2014 05:05 PM, Robert Hathaway wrote:
> I've got a program that reads a text file line by line (using std.stdio
> readln())

Consider using byLine() instead. (Important: byLine uses an internal buffer for the line; so, don't forget to make a copy if you want to store the line for later use.)

> and I'd like to refer to the line number when I send a message
> to stderr upon finding a mis-formatted line.  Is there a way to get the
> current line number?  Of course, I could create a counter and increment
> it with each call to readln, but is there a "cool" way of doing this?
>
> Okay, call me lazy... just don't call me late for dinner! :-)
>
> Robert

One cool way is a zipped sequence:

import std.stdio;
import std.range;

void main()
{
    foreach (i, line; zip(sequence!"n", File("deneme.txt").byLine)) {
        writefln("%s: %s", i, line);
    }
}

Ali

On Thursday, 5 June 2014 at 00:33:26 UTC, Ali Çehreli wrote:
> On 06/04/2014 05:05 PM, Robert Hathaway wrote:
>> I've got a program that reads a text file line by line (using std.stdio
>> readln())
>
> Consider using byLine() instead. (Important: byLine uses an internal buffer for the line; so, don't forget to make a copy if you want to store the line for later use.)
>
> > and I'd like to refer to the line number when I send a message
>> to stderr upon finding a mis-formatted line.  Is there a way to get the
>> current line number?  Of course, I could create a counter and increment
>> it with each call to readln, but is there a "cool" way of doing this?
>>
>> Okay, call me lazy... just don't call me late for dinner! :-)
>>
>> Robert
>
> One cool way is a zipped sequence:
>
> import std.stdio;
> import std.range;
>
> void main()
> {
>     foreach (i, line; zip(sequence!"n", File("deneme.txt").byLine)) {
>         writefln("%s: %s", i, line);
>     }
> }
>
> Ali

Once this[1] gets merged you'll be able to do this:

foreach (lineNum, line; File("deneme.txt").byLine().enumerate(1))
      writefln("%s: %s", lineNum, line);

Which is a bit more clear about the intent.

1. https://github.com/D-Programming-Language/phobos/pull/1866