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/* C++ Primer 4/e
* section 3.2 - String Standard Library

* exercise 3.10
* STATEMENT
* write a programme to strip the punctation from the string. */

#include <iostream>
#include <string>

int main()
{
std::cout << "Enter a string: ";
std::string a_word, stripped_word;
std::cin >> a_word;

for(std::string::size_type ix = 0; ix != a_word.size(); ++ix)
{
if(ispunct(a_word[ix]) == 0)
stripped_word[ix] = a_word[ix];
}

std::cout << stripped_word << std::endl;

return 0;
}

--
-- http://arnuld.blogspot.com

On Wed, 18 Jul 2007 14:07:59 +0500, arnuld wrote:

> /* C++ Primer 4/e
> * section 3.2 - String Standard Library
>
> * exercise 3.10
> * STATEMENT
> * write a programme to strip the punctation from the string. */
>
> #include <iostream>
> #include <string>
>
> int main()
> {
> std::cout << "Enter a string: ";
> std::string a_word, stripped_word;
> std::cin >> a_word;
>
> for(std::string::size_type ix = 0; ix != a_word.size(); ++ix)
> {
> if(ispunct(a_word[ix]) == 0)
> stripped_word[ix] = a_word[ix];
> }
>
> std::cout << stripped_word << std::endl;
>
> return 0;
> }


SORRY, i forgot to post the output:

[arnuld@arch cpp ]% g++ -ansi -pedantic -Wall -Wextra ex_03-10.cpp
[arnuld@arch cpp ]% ./a.out
Enter a string: comp.lang.c++

[arnuld@arch cpp ]%


you see, it does not prinit anything at all but it compiled successfully.
where is the bug ?


--
-- http://arnuld.blogspot.com

On Wed, 18 Jul 2007 14:07:59 +0500, arnuld wrote:

> /* C++ Primer 4/e
> * section 3.2 - String Standard Library
>
> * exercise 3.10
> * STATEMENT
> * write a programme to strip the punctation from the string. */
>
> #include <iostream>
> #include <string>
>
> int main()
> {
> std::cout << "Enter a string: ";
> std::string a_word, stripped_word;
> std::cin >> a_word;
>
> for(std::string::size_type ix = 0; ix != a_word.size(); ++ix)
> {
> if(ispunct(a_word[ix]) == 0)
> stripped_word[ix] = a_word[ix];

A std::string is not an open array, you can't just assign
to random non-existing positions.

stripped_word += a_word[ix];
or
stripped_word.append(a_word[ix]);

> }
>
> std::cout << stripped_word << std::endl;
>
> return 0;
> }
>

--
Obnoxious User

arnuld wrote:
> /* C++ Primer 4/e
> * section 3.2 - String Standard Library
>
> * exercise 3.10
> * STATEMENT
> * write a programme to strip the punctation from the string. */
>
> #include <iostream>
> #include <string>
>
> int main()
> {
> std::cout << "Enter a string: ";
> std::string a_word, stripped_word;
> std::cin >> a_word;
>
> for(std::string::size_type ix = 0; ix != a_word.size(); ++ix)
> {
> if(ispunct(a_word[ix]) == 0)
> stripped_word[ix] = a_word[ix];
> }
>
> std::cout << stripped_word << std::endl;
>
> return 0;
> }
>

Here is the fixed (hack) version:


#include <iostream>
#include <string>

int main()
{
std::cout << "Enter a string: ";
std::string a_word, stripped_word;
std::cin >> a_word;

for(std::string::size_type ix = 0; ix != a_word.size(); ++ix)
{
if(ispunct(a_word.at(ix)) == 0)
stripped_word.append(1,a_word.at(ix));
}

std::cout << stripped_word << std::endl;

return 0;
}

arnuld wrote:
> /* C++ Primer 4/e
> * section 3.2 - String Standard Library
>
> * exercise 3.10
> * STATEMENT
> * write a programme to strip the punctation from the string. */
>
> #include <iostream>
> #include <string>
>
> int main()
> {
> std::cout << "Enter a string: ";
> std::string a_word, stripped_word;
> std::cin >> a_word;
>
> for(std::string::size_type ix = 0; ix != a_word.size(); ++ix)
> {
> if(ispunct(a_word[ix]) == 0)
> stripped_word[ix] = a_word[ix];
> }
>
> std::cout << stripped_word << std::endl;
>
> return 0;
> }
>
As well as the other suggestions, you could use:

for( std::string::const_iterator ix = a_word.begin();
ix != a_word.end(); ++ix )
{
if(ispunct(*ix) == 0)
stripped_word += *ix;
}


--
Ian Collins.

> On Wed, 18 Jul 2007 09:26:44 +0000, Obnoxious User wrote:


> A std::string is not an open array, you can't just assign to random
> non-existing positions.

ok, got it


> stripped_word += a_word[ix];

this works. we are just concatenating 2 string objects. right ?


> stripped_word.append(a_word[ix]);

[arnuld@arch cpp ]% g++ -ansi -pedantic -Wall -Wextra ex_03-10.cpp
ex_03-10.cpp: In function ‘int main()’: ex_03-10.cpp:21: error: no
matching function for call to ‘std::basic_string<char,
std::char_traits<char>, std::allocator<char> >::append(char&)’
/usr/lib/gcc/i686-pc-linux-gnu/4.2.1/../../../../include/c++/4.2.1/bits/basic_string.tcc:330:
note: candidates are: std::basic_string<_CharT, _Traits, _Alloc>&
std::basic_string<_CharT, _Traits, _Alloc>::append(const
std::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char, _Traits
= std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i686-pc-linux-gnu/4.2.1/../../../../include/c++/4.2.1/bits/basic_string.tcc:347:
note: std::basic_string<_CharT, _Traits, _Alloc>&
std::basic_string<_CharT, _Traits, _Alloc>::append(const
std::basic_string<_CharT, _Traits, _Alloc>&, typename
_Alloc::rebind<_CharT>:ther::size_type, typename
_Alloc::rebind<_CharT>:ther::size_type) [with _CharT = char, _Traits =
std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i686-pc-linux-gnu/4.2.1/../../../../include/c++/4.2.1/bits/basic_string.tcc:303:
note: std::basic_string<_CharT, _Traits, _Alloc>&
std::basic_string<_CharT, _Traits, _Alloc>::append(const _CharT*, typename
_Alloc::rebind<_CharT>:ther::size_type) [with _CharT = char, _Traits =
std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i686-pc-linux-gnu/4.2.1/../../../../include/c++/4.2.1/bits/basic_string.h:824:
note: std::basic_string<_CharT, _Traits, _Alloc>&
std::basic_string<_CharT, _Traits, _Alloc>::append(const _CharT*) [with
_CharT = char, _Traits = std::char_traits<char>, _Alloc =
std::allocator<char>] <near match>
/usr/lib/gcc/i686-pc-linux-gnu/4.2.1/../../../../include/c++/4.2.1/bits/basic_string.tcc:286:
note: std::basic_string<_CharT, _Traits, _Alloc>&
std::basic_string<_CharT, _Traits, _Alloc>::append(typename
_Alloc::rebind<_CharT>:ther::size_type, _CharT) [with _CharT = char,
_Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
[arnuld@arch cpp ]%
[arnuld@arch cpp ]% g++ --version
g++ (GCC) 4.2.1 20070704 (prerelease) Copyright (C) 2007 Free Software
Foundation, Inc. This is free software; see the source for copying
conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.

[arnuld@arch cpp ]%


--
-- http://arnuld.blogspot.com

arnuld wrote:
> [..]
> can you tell me how this works or just point me to someplave which
> explains that:
>
> stripped_word.append(1,a_word.at(ix));
>
> i mean, what is "1" doing here ? and why (ix) rather than [ix] ? i am
> at halfway of chapter 3 so i have not come across this "append" member
> function. just covered "size" and "empty" till yet.

RTFM. 'append' is overloaded and one of them takes a number (N) and
the character and appends a string generated from N characters. There
is a constructor that does similar stuff, BTW.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

> On Wed, 18 Jul 2007 12:04:02 +0200, anon wrote:

> Here is the fixed (hack) version:



> #include <iostream>
> #include <string>
>
> int main()
> {
> std::cout << "Enter a string: ";
> std::string a_word, stripped_word;
> std::cin >> a_word;
>
> for(std::string::size_type ix = 0; ix != a_word.size(); ++ix)
> {
> if(ispunct(a_word.at(ix)) == 0)
> stripped_word.append(1,a_word.at(ix));
> }
>
> std::cout << stripped_word << std::endl;
>
> return 0;


can you tell me how this works or just point me to someplave which
explains that:

stripped_word.append(1,a_word.at(ix));

i mean, what is "1" doing here ? and why (ix) rather than [ix] ? i am at
halfway of chapter 3 so i have not come across this "append" member
function. just covered "size" and "empty" till yet.




--
-- http://arnuld.blogspot.com

Victor Bazarov wrote:
> arnuld wrote:
>> [..]
>> can you tell me how this works or just point me to someplave which
>> explains that:
>>
>> stripped_word.append(1,a_word.at(ix));
>>
>> i mean, what is "1" doing here ? and why (ix) rather than [ix] ? i am
>> at halfway of chapter 3 so i have not come across this "append" member
>> function. just covered "size" and "empty" till yet.
>
> RTFM. 'append' is overloaded and one of them takes a number (N) and
> the character and appends a string generated from N characters. There
> is a constructor that does similar stuff, BTW.

These guys got very good references:
http://www.cppreference.com/cppstring/index.html
and should answer all questions.


PS If anyone know better references, please let me know.
www.cppreference.com is missing lots of stuff

On 2007-07-18 18:17, anon wrote:
> Victor Bazarov wrote:
>> arnuld wrote:
>>> [..]
>>> can you tell me how this works or just point me to someplave which
>>> explains that:
>>>
>>> stripped_word.append(1,a_word.at(ix));
>>>
>>> i mean, what is "1" doing here ? and why (ix) rather than [ix] ? i am
>>> at halfway of chapter 3 so i have not come across this "append" member
>>> function. just covered "size" and "empty" till yet.
>>
>> RTFM. 'append' is overloaded and one of them takes a number (N) and
>> the character and appends a string generated from N characters. There
>> is a constructor that does similar stuff, BTW.
>
> These guys got very good references:
> http://www.cppreference.com/cppstring/index.html
> and should answer all questions.
>
>
> PS If anyone know better references, please let me know.
> www.cppreference.com is missing lots of stuff

www.cplusplus.com is quite complete I think, but I like the simplicity
of www.cppreference.com better.

--
Erik Wikström