«

Hi,
In java, there is an 'indexOf' function in String which does this:

indexOf(String str)
Returns the index within this string of the first occurrence
of the specified substring.

is there anything like that in c?

The closest thing I can find is strchr, but it check for a character,
not a substring?

Thank you.

said:

> Hi,
> In java, there is an 'indexOf' function in String which does this:
>
> indexOf(String str)
> Returns the index within this string of the first occurrence
> of the specified substring.
>
> is there anything like that in c?
>
> The closest thing I can find is strchr, but it check for a character,
> not a substring?

strstr returns a pointer to the substring - if this is non-NULL,
subtract the address of the main string from it to get the index.

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
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"Richard Heathfield" <> wrote in message
news:tZ-...
> said:
>
>> Hi,
>> In java, there is an 'indexOf' function in String which does this:
>>
>> indexOf(String str)
>> Returns the index within this string of the first occurrence
>> of the specified substring.
>>
>> is there anything like that in c?
>>
>> The closest thing I can find is strchr, but it check for a character,
>> not a substring?
>
> strstr returns a pointer to the substring - if this is non-NULL,
> subtract the address of the main string from it to get the index.
>
ie;

char *str = "astring";
char *substring = "in";
char *ptr;
ptrdiff_t index; /* should be an int. Horrid horrid horrid */

ptr = strstr(str, substring);
if(ptr)
{
index = ptr - str;
printf("your substring was found at postion %d (0-based)\n", (int)
index);
}

As an exercise to the regs, why do we need that horrid, horrid cast in the
call to printf?

--
Free games and programming goodies.
http://www.personal.leeds.ac.uk/~bgy1mm

Malcolm McLean wrote:
> char *str = "astring";
> char *substring = "in";
> char *ptr;
> ptrdiff_t index; /* should be an int. Horrid horrid horrid */
>
> ptr = strstr(str, substring);
> if(ptr)
> {
> index = ptr - str;
> printf("your substring was found at postion %d (0-based)\n", (int)
> index);
> }
>
> As an exercise to the regs, why do we need that horrid, horrid cast in the
> call to printf?

You don't. You're already assuming that index will fit in an int, so you can
just change the declaration of index to match.

schrieb:
> Hi,
> In java, there is an 'indexOf' function in String which does this:
>
> indexOf(String str)
> Returns the index within this string of the first occurrence
> of the specified substring.
>
> is there anything like that in c?
>
> The closest thing I can find is strchr, but it check for a character,
> not a substring?
>
> Thank you.
>

hello,

you can use instead the function
char * strstr(const char *s1, const char *s2)

from string.h

Ralf

"Harald van D?k" <> wrote in message
news:f79r9j$uaq$...
> Malcolm McLean wrote:
>> char *str = "astring";
>> char *substring = "in";
>> char *ptr;
>> ptrdiff_t index; /* should be an int. Horrid horrid horrid */
>>
>> ptr = strstr(str, substring);
>> if(ptr)
>> {
>> index = ptr - str;
>> printf("your substring was found at postion %d (0-based)\n", (int)
>> index);
>> }
>>
>> As an exercise to the regs, why do we need that horrid, horrid cast in
>> the
>> call to printf?
>
> You don't. You're already assuming that index will fit in an int, so you
> can
> just change the declaration of index to match.
>
My point exactly. We fill the language with gibberish types, which don't
actually gain anything because eventually some fucntion somewhere will
expect an int.
Join the campaign for 64 bit ints and this nonsense will fade away.

--
Free games and programming goodies.
http://www.personal.leeds.ac.uk/~bgy1mm

Malcolm McLean wrote:
> "Harald van D?k" <> wrote in message
> news:f79r9j$uaq$...
>> Malcolm McLean wrote:
>>> char *str = "astring";
>>> char *substring = "in";
>>> char *ptr;
>>> ptrdiff_t index; /* should be an int. Horrid horrid horrid */
>>>
>>> ptr = strstr(str, substring);
>>> if(ptr)
>>> {
>>> index = ptr - str;
>>> printf("your substring was found at postion %d (0-based)\n", (int)
>>> index);
>>> }
>>>
>>> As an exercise to the regs, why do we need that horrid, horrid cast in
>>> the
>>> call to printf?
>>
>> You don't. You're already assuming that index will fit in an int, so you
>> can
>> just change the declaration of index to match.
>>
> My point exactly. We fill the language with gibberish types, which don't
> actually gain anything because eventually some fucntion somewhere will
> expect an int.

Which function is that, here? You don't need to assume index will fit in an
int, you just chose to for convenience.

<> wrote in message
news: oups.com...
> Hi,
> In java, there is an 'indexOf' function in String which does this:
>
> indexOf(String str)
> Returns the index within this string of the first occurrence
> of the specified substring.
>
> is there anything like that in c?
>
> The closest thing I can find is strchr, but it check for a character,
> not a substring?

If you know strchr() searches a string for a char, did it not occur to you
to check if strstr() searches a string for a string?

However, both return a pointer to the first instance found (or NULL, if
none) instead of an index. If the returned value was non-NULL, subtract the
pointer to the original string from the returned value to get the index.

S

--
Stephen Sprunk "Those people who think they know everything
CCIE #3723 are a great annoyance to those of us who do."
K5SSS --Isaac Asimov


--
Posted via a free Usenet account from http://www.teranews.com

"Harald van Dijk" <> wrote in message
news:f7a29h$bd$...
> Malcolm McLean wrote:
>> "Harald van D?k" <> wrote in message
>> news:f79r9j$uaq$...
>>> Malcolm McLean wrote:
>>>> char *str = "astring";
>>>> char *substring = "in";
>>>> char *ptr;
>>>> ptrdiff_t index; /* should be an int. Horrid horrid horrid */
>>>>
>>>> ptr = strstr(str, substring);
>>>> if(ptr)
>>>> {
>>>> index = ptr - str;
>>>> printf("your substring was found at postion %d (0-based)\n", (int)
>>>> index);
>>>> }
>>>>
>>>> As an exercise to the regs, why do we need that horrid, horrid cast in
>>>> the
>>>> call to printf?
>>>
>>> You don't. You're already assuming that index will fit in an int, so you
>>> can
>>> just change the declaration of index to match.
>>>
>> My point exactly. We fill the language with gibberish types, which don't
>> actually gain anything because eventually some fucntion somewhere will
>> expect an int.
>
> Which function is that, here? You don't need to assume index will fit in
> an
> int, you just chose to for convenience.
>
printf(). There probably is a specifier for ptrdiff_t in C99, but I doubt
you can guarantee its presence.

--
Free games and programming goodies.
http://www.personal.leeds.ac.uk/~bgy1mm

On Sat, 14 Jul 2007 07:29:35 +0100, Malcolm McLean wrote:

>
> "Richard Heathfield" <> wrote in message
> news:tZ-...
>> said:
>>
>>> Hi,
>>> In java, there is an 'indexOf' function in String which does this:
>>>
>>> indexOf(String str)
>>> Returns the index within this string of the first occurrence
>>> of the specified substring.
>>>
>>> is there anything like that in c?
>>>
>>> The closest thing I can find is strchr, but it check for a character,
>>> not a substring?
>>
>> strstr returns a pointer to the substring - if this is non-NULL,
>> subtract the address of the main string from it to get the index.
>>
> ie;
>
> char *str = "astring";
> char *substring = "in";
> char *ptr;
> ptrdiff_t index; /* should be an int. Horrid horrid horrid */
>
> ptr = strstr(str, substring);
> if(ptr)
> {
> index = ptr - str;
> printf("your substring was found at postion %d (0-based)\n", (int)
> index);
> }
>
> As an exercise to the regs, why do we need that horrid, horrid cast in the
> call to printf?
Because you feared enough that the magnitude of (ptr - str) could
ever be > 32767, that you didn't declare index as an int.
Otherwise you could declare it as a long and use "%ld" in printf.
--
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"Never attribute to malice that which can be adequately explained
by stupidity." -- R. J. Hanlon (?)