convert string into an array

[Sudzzz]

Hi,
I'm trying to convert a string something like this
"{201,23,240,56 ,23,45,34,23}" into an array in C++
Please help.
Thanks,
Sudzzz

[Jim Langston]

"James Kanze" <ja*********@gm ail.comwrote in message
news:11******** **************@ n60g2000hse.goo glegroups.com.. .
On Jul 3, 10:46 pm, "Jim Langston" <tazmas...@rock etmail.comwrote :

I would use a stringstream.

Just curious, but why a stringstream, and not an istringstream?

I don't know. I use stringstream for all types of conversion and it works.
What real advantage would istringstream give me?

[...]

std::string str_array = "{201,23,240,56 ,23,45,34,23}";
std::stringstre am Buffer;
Buffer << str_array;

Why those two lines, instead of simply:

std::istringstr eam Buffer( str_array ) ;

Becuase I normally use stringstring in one of my templates:

template<typena me T, typename F T StrmConvert( const F from )
{
std::stringstre am temp;
temp << from;
T to = T();
temp >to;
return to;
}

If I change this to

std::string temp( from );

then I get compiler warnings at times depending on F.

warning C4244: 'argument' : conversion from 'const float' to
'std::_Iosb<_Du mmy>::openmode' , possible loss of data

and I go for 0% warnings in my code. I know that the form I use doesn't
give any warnings.

char Trash;
Buffer >Trash; // Throw away (

Throw away, or verify, as a syntax check? (In my experience,
you can never verify input too much.)

Agreed, but in most instances where I'm using stringstream for conversion
I've verified the data before I try to convert it, or the output makes it
obvious there was a problem. With user input data I would definately do
syntax checking of the string before/during/after the conversion.

int Value;
std::vector<int Data;
while ( Buffer >Value )

while ( Buffer >Value && Trash != '}' )

This is really not needed though, unless there is extraneous data after
the ) such as

{201,23,240,56, 23,45,34,23}75

etc... (not going to comment on the rest)

{

And

if ( Trash != (Data.empty() ? '{' : ',') ) {
Buffer.setstate ( std::ios::failb it ) ;
}

here.

Data.push_back( Value );
Buffer >Trash; // Throw away , or )
}

And a final error check:

if ( ! (Buffer >std::ws && Buffer.get() == EOF ) {
error ...
}

// Display vector data
for ( std::vector<int >::iterator it = Data.begin(); it !=
Data.end();
++it )
std::cout << *it << " ";
}

(But I like your basic algorithm better than the one I
suggested.)

[James Kanze]

On Jul 5, 4:36 am, "Jim Langston" <tazmas...@rock etmail.comwrote :

"James Kanze" <james.ka...@gm ail.comwrote in message
news:11******** **************@ n60g2000hse.goo glegroups.com.. .
On Jul 3, 10:46 pm, "Jim Langston" <tazmas...@rock etmail.comwrote :

I would use a stringstream.

Just curious, but why a stringstream, and not an istringstream?

I don't know. I use stringstream for all types of conversion
and it works. What real advantage would istringstream give
me?

It seems clearer to me if you're only going to be reading. I
use istringstream for input conversions (from text to whatever),
and ostringstream for output conversions (to text from
whatever). Somehow, it just seems clearer to say up front what
I'm going to do.

[...]

std::string str_array = "{201,23,240,56 ,23,45,34,23}";
std::stringstre am Buffer;
Buffer << str_array;

Why those two lines, instead of simply:

std::istringstr eam Buffer( str_array ) ;

Becuase I normally use stringstring in one of my templates:

template<typena me T, typename F T StrmConvert( const F from )
{
std::stringstre am temp;
temp << from;
T to = T();
temp >to;
return to;
}

Sort of boost::lexical_ cast, in sum. That's a different
context. (I'm not totally convinced that boost::lexical_ cast is
a good idea. I'm not too hot on the idea that you can convert
anything to anything else, and never get a compiler error.)

If I change this to

std::string temp( from );

then I get compiler warnings at times depending on F.

warning C4244: 'argument' : conversion from 'const float' to
'std::_Iosb<_Du mmy>::openmode' , possible loss of data

and I go for 0% warnings in my code. I know that the form I
use doesn't give any warnings.

One could argue that since you're doing two conversions, you
should have two conversion objects, i.g.:

std::istringstr eam in ;
in << from ;
std::ostringstr eam out( in.str() ) ;
T to ;
out >to ;
return to ;

I'm not sure. As I said, I'm not too hot on this idea to begin
with. (If I were doing it, I'd certainly add a lot of error
handling. But I presume you've just stripped it out to make it
shorter for posting.)

char Trash;
Buffer >Trash; // Throw away (

Throw away, or verify, as a syntax check? (In my experience,
you can never verify input too much.)

Agreed, but in most instances where I'm using stringstream for
conversion I've verified the data before I try to convert it,
or the output makes it obvious there was a problem.

In most cases, I have too. Nothing like boost::regex
beforehand, to know what I'm dealing with. (But I thought I'd
mentionned that.) If you don't know the length in advance,
however, it's probably easier to do the checking dynamically.

I don't know the full context either. It might be worth
considering creating a decorator type for which you define an
operator>>, and use that, something like:

source >ArrayReader( array ) ;

With user input data I would definately do syntax checking of
the string before/during/after the conversion.

int Value;
std::vector<int Data;
while ( Buffer >Value )

while ( Buffer >Value && Trash != '}' )

This is really not needed though, unless there is extraneous data after
the ) such as

{201,23,240,56, 23,45,34,23}75

etc...

Yes. The real question is whether the string has been format
checked before hand, or not. If it has, then no further
checking should be necessary. If it hasn't, you probably want
to verify everything.

--
James Kanze (GABI Software) email:ja******* **@gmail.com
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