sscanf regex

[j0mbolar]

say you have char buf[] = "string1 string2 string3";

then you want to use sscanf to match "string3" and store
it into another array.

so:

char buf[] = "string1 string2 string3";
char array[100];

sscanf(buf, "what format string should we use?", array);

[Eric Sosman]

Re: sscanf regex

j0mbolar wrote:[color=blue]
> say you have char buf[] = "string1 string2 string3";
>
> then you want to use sscanf to match "string3" and store
> it into another array.
>
> so:
>
> char buf[] = "string1 string2 string3";
> char array[100];
>
> sscanf(buf, "what format string should we use?", array);[/color]

If I understand your intent correctly (not certain):

if (sscanf(buf, "%*s%*s%99s ", array) == 1)
...

is what you want. This format

- Skips any leading white space, gathers the
longest possible batch of non-white characters,
and doesn't store them anywhere, then

- Skips any more white space, gathers another batch
of non-white characters, and doesn't store them
anywhere, then

- Skips any more white space, gathers a third batch
of non-white characters (but no more than 99 of
them), stores them in `array', and returns 1 to
indicate that it has converted and stored one
field.

If the scan reaches the end of `buf' before finding all
three non-white strings, sscanf() returns either zero or
EOF depending on the exact circumstances.

--
Eric.Sosman@sun .com

[Arthur J. O'Dwyer]

Re: sscanf regex


On Wed, 16 Jun 2004, j0mbolar wrote:[color=blue]
>
> say you have char buf[] = "string1 string2 string3";
> then you want to use sscanf to match "string3" and store
> it into another array.
>
> char buf[] = "string1 string2 string3";
> char array[100];
>
> sscanf(buf, "what format string should we use?", array);[/color]

sscanf(buf, "%*s%*s%s", array);

would be the simplest, I think.

-Arthur

[Irrwahn Grausewitz]

Re: sscanf regex

j0mbolar@engine er.com (j0mbolar) wrote:[color=blue]
>say you have char buf[] = "string1 string2 string3";
>
>then you want to use sscanf to match "string3" and store
>it into another array.
>
>so:
>
>char buf[] = "string1 string2 string3";
>char array[100];
>
>sscanf(buf, "what format string should we use?", array);[/color]

sscanf( buf, "%*[^ ] %*[^ ] %s", array );


Regards
--
Irrwahn Grausewitz (irrwahn33@free net.de)
welcome to clc: http://www.ungerhu.com/jxh/clc.welcome.txt
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[Dan Pop]

Re: sscanf regex

In <2d31a9f9.04061 61255.5f9b0fd1@ posting.google. com> j0mbolar@engine er.com (j0mbolar) writes:
[color=blue]
>say you have char buf[] = "string1 string2 string3";
>
>then you want to use sscanf to match "string3" and store
>it into another array.
>
>so:
>
>char buf[] = "string1 string2 string3";
>char array[100];
>
>sscanf(buf, "what format string should we use?", array);[/color]

You don't want to use sscanf for this purpose.

#define TARGET "string3"
char *p;

if ((p = strstr(buf, TARGET)) != NULL) {
memcpy(array, p, strlen(TARGET)) ;
array[strlen(TARGET)] = 0;
}

Of course, for this trivial example, you don't need to extract the
pattern from the input string, so

if (strstr(buf, TARGET) != NULL) strcpy(array, TARGET);

will do.

The closest you can get in the way of regex support in standard C are
strstr(), str[c]spn(), strpbrk() and the %[ conversion specifier of
sscanf.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de

[Dan Pop]

Re: sscanf regex

In <40D0BC4F.50307 04@sun.com> Eric Sosman <Eric.Sosman@su n.com> writes:
[color=blue]
>j0mbolar wrote:[color=green]
>> say you have char buf[] = "string1 string2 string3";
>>
>> then you want to use sscanf to match "string3" and store[/color][/color]
^^^^^^^^[color=blue][color=green]
>> it into another array.
>>
>> so:
>>
>> char buf[] = "string1 string2 string3";
>> char array[100];
>>
>> sscanf(buf, "what format string should we use?", array);[/color]
>
> If I understand your intent correctly (not certain):
>
> if (sscanf(buf, "%*s%*s%99s ", array) == 1)
> ...
>
>is what you want. This format[/color]

Could you please explain how is this code checking the presence of
"string3" in buf? I suppose this what the OP meant by "to match".

Unless I'm missing something obvious, the OP wasn't asking about how to
extract the third word in buf.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de

[Eric Sosman]

Re: sscanf regex

Dan Pop wrote:[color=blue]
> In <40D0BC4F.50307 04@sun.com> Eric Sosman <Eric.Sosman@su n.com> writes:
>
>[color=green]
>>j0mbolar wrote:
>>[color=darkred]
>>>say you have char buf[] = "string1 string2 string3";
>>>
>>>then you want to use sscanf to match "string3" and store[/color][/color]
>
> ^^^^^^^^
>[color=green][color=darkred]
>>>it into another array.
>>>
>>>so:
>>>
>>>char buf[] = "string1 string2 string3";
>>>char array[100];
>>>
>>>sscanf(buf , "what format string should we use?", array);[/color]
>>
>> If I understand your intent correctly (not certain):
>>
>> if (sscanf(buf, "%*s%*s%99s ", array) == 1)
>> ...
>>
>>is what you want. This format[/color]
>
>
> Could you please explain how is this code checking the presence of
> "string3" in buf? I suppose this what the OP meant by "to match".
>
> Unless I'm missing something obvious, the OP wasn't asking about how to
> extract the third word in buf.[/color]

Well, I *said* I wasn't sure I'd understood the O.P.'s
intent. I thought about offering

if (strchr(buf, "string3") != NULL)
strcpy(array, "string3");

.... but that seemed pointless, so I tried to look for another
interpretation of an imprecise problem statement. And then I
told him what my "solution" did, just in case I was solving
the wrong problem.

Now I'll get back to devising the circuitry behind the
DWIM instruction in the next-generation SPARC ;-)

--
Eric.Sosman@sun .com

[Alex Monjushko]

Re: sscanf regex

Eric Sosman <Eric.Sosman@su n.com> wrote:[color=blue]
> Dan Pop wrote:[/color]

[snip]
[color=blue][color=green]
>> Could you please explain how is this code checking the presence of
>> "string3" in buf? I suppose this what the OP meant by "to match".
>>
>> Unless I'm missing something obvious, the OP wasn't asking about how to
>> extract the third word in buf.[/color][/color]
[color=blue]
> Well, I *said* I wasn't sure I'd understood the O.P.'s
> intent. I thought about offering[/color]
[color=blue]
> if (strchr(buf, "string3") != NULL)[/color]
^^^^^^[color=blue]
> strcpy(array, "string3");[/color]

I think you mean 'strstr'.

--
Alex Monjushko (monjushko@hotm ail.com)

[Irrwahn Grausewitz]

Re: sscanf regex

Dan.Pop@cern.ch (Dan Pop) wrote:[color=blue]
>In <40D0BC4F.50307 04@sun.com> Eric Sosman <Eric.Sosman@su n.com> writes:
>[color=green]
>>j0mbolar wrote:[color=darkred]
>>> say you have char buf[] = "string1 string2 string3";
>>>
>>> then you want to use sscanf to match "string3" and store[/color][/color]
> ^^^^^^^^[color=green][color=darkred]
>>> it into another array.[/color][/color][/color]
....[color=blue][color=green]
>> If I understand your intent correctly (not certain):
>>
>> if (sscanf(buf, "%*s%*s%99s ", array) == 1)
>> ...[/color]
>
>Could you please explain how is this code checking the presence of
>"string3" in buf? I suppose this what the OP meant by "to match".[/color]

Er... well, maybe, but it doesn't make much sense to look for a
literal occurrence of a certain substring *and then copy that to
another array*, does it?!?
[color=blue]
>Unless I'm missing something obvious, the OP wasn't asking about how to
>extract the third word in buf.[/color]

As I understood, the OP was asking exactly about that: how to
extract the last of three blank separated words from a given
string, but used the word 'match' in a less strict sense than
you inferred. I may still be mistaken, though.

Regards
--
Irrwahn Grausewitz (irrwahn33@free net.de)
welcome to clc: http://www.ungerhu.com/jxh/clc.welcome.txt
clc faq-list : http://www.faqs.org/faqs/C-faq/faq/
clc OT guide : http://benpfaff.org/writings/clc/off-topic.html

[Dan Pop]

Re: sscanf regex

In <40D1C00A.70008 08@sun.com> Eric Sosman <Eric.Sosman@su n.com> writes:
[color=blue]
>Dan Pop wrote:[color=green]
>> In <40D0BC4F.50307 04@sun.com> Eric Sosman <Eric.Sosman@su n.com> writes:
>>
>>[color=darkred]
>>>j0mbolar wrote:
>>>
>>>>say you have char buf[] = "string1 string2 string3";
>>>>
>>>>then you want to use sscanf to match "string3" and store[/color]
>>
>> ^^^^^^^^
>>[color=darkred]
>>>>it into another array.
>>>>
>>>>so:
>>>>
>>>>char buf[] = "string1 string2 string3";
>>>>char array[100];
>>>>
>>>>sscanf(bu f, "what format string should we use?", array);
>>>
>>> If I understand your intent correctly (not certain):
>>>
>>> if (sscanf(buf, "%*s%*s%99s ", array) == 1)
>>> ...
>>>
>>>is what you want. This format[/color]
>>
>>
>> Could you please explain how is this code checking the presence of
>> "string3" in buf? I suppose this what the OP meant by "to match".
>>
>> Unless I'm missing something obvious, the OP wasn't asking about how to
>> extract the third word in buf.[/color]
>
> Well, I *said* I wasn't sure I'd understood the O.P.'s
>intent. I thought about offering
>
> if (strchr(buf, "string3") != NULL)
> strcpy(array, "string3");
>
>... but that seemed pointless,[/color]

It was far less pointless than your "solution", because it was
actually doing the pattern matching required by the OP and *conditionally*
storing the matched pattern into array.
[color=blue]
>so I tried to look for another
>interpretati on of an imprecise problem statement.[/color]

1. The problem statement was as precise as you can get. It's just that
sscanf can't be used as part of the solution.

2. Interpreting a request for pattern matching as a request for finding
the third word in a string doesn't make any sense to me.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de

[Dan Pop]

Re: sscanf regex

In <63j3d091hkp5u7 fr375h1kaa666p6 n91r6@4ax.com> Irrwahn Grausewitz <irrwahn33@free net.de> writes:
[color=blue]
>Dan.Pop@cern.c h (Dan Pop) wrote:[color=green]
>>In <40D0BC4F.50307 04@sun.com> Eric Sosman <Eric.Sosman@su n.com> writes:
>>[color=darkred]
>>>j0mbolar wrote:
>>>> say you have char buf[] = "string1 string2 string3";
>>>>
>>>> then you want to use sscanf to match "string3" and store[/color]
>> ^^^^^^^^[color=darkred]
>>>> it into another array.[/color][/color]
>...[color=green][color=darkred]
>>> If I understand your intent correctly (not certain):
>>>
>>> if (sscanf(buf, "%*s%*s%99s ", array) == 1)
>>> ...[/color]
>>
>>Could you please explain how is this code checking the presence of
>>"string3" in buf? I suppose this what the OP meant by "to match".[/color]
>
>Er... well, maybe, but it doesn't make much sense to look for a
>literal occurrence of a certain substring *and then copy that to
>another array*, does it?!?[/color]

Not as a *complete* programming problem, but it is perfectly sensible
as *part* of a programming problem, where the contents of the other
array may depend on a sequence of tests:

- if the pattern match succeeds, it is the pattern
- else if ..., it is ...
- else it is a default value
[color=blue][color=green]
>>Unless I'm missing something obvious, the OP wasn't asking about how to
>>extract the third word in buf.[/color]
>
>As I understood, the OP was asking exactly about that: how to
>extract the last of three blank separated words from a given
>string, but used the word 'match' in a less strict sense than
>you inferred. I may still be mistaken, though.[/color]

The usage of the word "regex" in the subject line is a very strong
clue that he used the word "match" as in a regular expression context.

Otherwise, the straightforward problem description would have been:
"how can I use sscanf to extract the third word in a string?", but
I strongly suspect that the OP could figure out the answer by himself.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de