• Damian (3/3) Jul 04 2013 Why don't these functions take a length parameter, like strcmp
• bearophile (5/8) Jul 04 2013 Probably slicing of their inputs, or using std.range.take() of
• Damian (19/27) Jul 04 2013 Ah but with slicing the inputs, you must check the length first
• bearophile (23/38) Jul 04 2013 To compare if two strings (or char arrays) are equal use ==, or
• Jonathan M Davis (8/24) Jul 04 2013 Except that cmp doesn't check the length. It just keeps popping elements...
• Damian (4/35) Jul 04 2013 In the example I gave startsWith is fine, but I also need case

"Damian" <damianday hotmail.co.uk> writes:

Why don't these functions take a length parameter, like strcmp 
and memcmp?
Is it worth making an enhancement request for such?

"bearophile" <bearophileHUGS lycos.com> writes:

Damian:

 Why don't these functions take a length parameter, like strcmp 
 and memcmp?
 Is it worth making an enhancement request for such?

Probably slicing of their inputs, or using std.range.take() of 
their inputs, is enough. Do you agree?

Bye,
bearophile

"Damian" <damianday hotmail.co.uk> writes:

On Thursday, 4 July 2013 at 22:02:06 UTC, bearophile wrote:
 Damian:

 Why don't these functions take a length parameter, like strcmp 
 and memcmp?
 Is it worth making an enhancement request for such?

 Probably slicing of their inputs, or using std.range.take() of 
 their inputs, is enough. Do you agree?

 Bye,
 bearophile


Ah but with slicing the inputs, you must check the length first
so that you don't get an out of bounds error. I would prefer it 
if cmp
did this for me, since it is going to check lengths anyway. 
Example below.

private void ParsePacket(in char[] data)
{
     static string Good = "GOOD";
     static string Bad = "BAD";

     if (data.length >= Good.length) // Prefer not to do this check
     {
         if (std.algorithm.cmp(data[0 .. Good.length], Good) == 0)
     }
     else if
     {
         // Check Bad, and so on
     }
}

"bearophile" <bearophileHUGS lycos.com> writes:

Damian:

 private void ParsePacket(in char[] data)
 {
     static string Good = "GOOD";
     static string Bad = "BAD";

     if (data.length >= Good.length) // Prefer not to do this 
 check
     {
         if (std.algorithm.cmp(data[0 .. Good.length], Good) == 
 0)
     }
     else if
     {
         // Check Bad, and so on
     }
 }

To compare if two strings (or char arrays) are equal use ==, or 
use a switch.

For your case you can use:


import std.stdio, std.string;

void parsePacket(in char[] data) {
     if (data.startsWith("GOOD")) {
         "very good".writeln;
     } else if (data.startsWith("BAD")) {
         "very bad".writeln;
     } else {
         "something else".writeln;
         // ...
     }
}

void main() {
     parsePacket("BAD_DAY");
}


Note that idiomatic D variables and functions usually start with 
a lowercase. It's better to ask similar questions in the D.learn 
newsgroup.

Bye,
bearophile

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Friday, July 05, 2013 00:36:02 Damian wrote:
 On Thursday, 4 July 2013 at 22:02:06 UTC, bearophile wrote:
 Damian:
 Why don't these functions take a length parameter, like strcmp
 and memcmp?
 Is it worth making an enhancement request for such?

 
 Probably slicing of their inputs, or using std.range.take() of
 their inputs, is enough. Do you agree?
 
 Bye,
 bearophile

 
 Ah but with slicing the inputs, you must check the length first
 so that you don't get an out of bounds error. I would prefer it
 if cmp
 did this for me, since it is going to check lengths anyway.

Except that cmp doesn't check the length. It just keeps popping elements until 
one of the two ranges is empty. Taking a length which it had to check would 
make it _less_ efficient, not more. The correct thing to do here is indeed to 
slice the range if it can be sliced or to use take if it can't be sliced. And 
if you want to slice the range and are worried about length, then just use min 
to make sure that you don't pass a length which is too large.

- Jonathan M Davis

"Damian" <damianday hotmail.co.uk> writes:

On Thursday, 4 July 2013 at 23:10:12 UTC, Jonathan M Davis wrote:
 On Friday, July 05, 2013 00:36:02 Damian wrote:
 On Thursday, 4 July 2013 at 22:02:06 UTC, bearophile wrote:
 Damian:
 Why don't these functions take a length parameter, like 
 strcmp
 and memcmp?
 Is it worth making an enhancement request for such?

 
 Probably slicing of their inputs, or using std.range.take() 
 of
 their inputs, is enough. Do you agree?
 
 Bye,
 bearophile

 
 Ah but with slicing the inputs, you must check the length first
 so that you don't get an out of bounds error. I would prefer it
 if cmp
 did this for me, since it is going to check lengths anyway.

 Except that cmp doesn't check the length. It just keeps popping 
 elements until
 one of the two ranges is empty. Taking a length which it had to 
 check would
 make it _less_ efficient, not more. The correct thing to do 
 here is indeed to
 slice the range if it can be sliced or to use take if it can't 
 be sliced. And
 if you want to slice the range and are worried about length, 
 then just use min
 to make sure that you don't pass a length which is too large.

 - Jonathan M Davis

In the example I gave startsWith is fine, but I also need case 
insensitive comparison, take and icmp, however, does seem to fit 
the bill perfectly.