ifsteam

[Alex Buell]

Why do I have to do the following if I want to open a file for reading
like
string filename = "data.txt";
ifstream ifs(filename.c_str());

I'd have thought that it would be quite elegant to do

ifstream ifs(filename);

instead!

--
http://www.munted.org.uk

Take a nap, it saves lives.

[pj_hern]

"Alex Buell" <al********@munted.org.uk> wrote in message news:20060404001936.de426068.al********@munted.org .uk...
| Why do I have to do the following if I want to open a file for reading
| like
| string filename = "data.txt";
| ifstream ifs(filename.c_str());
|
| I'd have thought that it would be quite elegant to do
|
| ifstream ifs(filename);
|
| instead!
|

What is preventing you from doing so?

#include <fstream>
#include <string>

class IFStream
{
std::ifstream m_ifs;
public:
IFStream(std::string s_fn) : m_ifs(s_fn.c_str()) { }
~IFSTream() { }
...
};

int main()
{
std::string file("test.bin");
IFStream( file );
}

[BobR]

Alex Buell wrote in message
<20********************************@munted.org.uk> ...

Why do I have to do the following if I want to open a file for reading
like
string filename = "data.txt";
ifstream ifs(filename.c_str());

I'd have thought that it would be quite elegant to do

ifstream ifs(filename);

instead!

Because you defined 'string' wrong.

typedef char const * string;
string filename( "data.txt" );
std::ifstream ifs( filename );
if( not ifs ){
std::cerr<<"\nError opening file\n";
}

And, you don't 'have to do' it that way:

ifstream ifs( "data.txt" );

--
Bob <G> R
POVrookie

[Alex Buell]

On Mon, 3 Apr 2006 21:57:25 -0400 "pj_hern" <pj*****@none.none> waved a
wand and this message magically appeared:

What is preventing you from doing so?

#include <fstream>
#include <string>

class IFStream
{
std::ifstream m_ifs;
public:
IFStream(std::string s_fn) : m_ifs(s_fn.c_str()) { }
~IFSTream() { }
...
};

int main()
{
std::string file("test.bin");
IFStream( file );
}

Oh yeah, good idea. But why use a c_str() with ifstream when it's so
simple to add an overloaded member function that takes a std::string?

--
http://www.munted.org.uk

Take a nap, it saves lives.

[Jim Langston]

"Alex Buell" <al********@munted.org.uk> wrote in message
news:20060404092632.2c15d10d.al********@munted.org .uk...

On Mon, 3 Apr 2006 21:57:25 -0400 "pj_hern" <pj*****@none.none> waved a
wand and this message magically appeared:

What is preventing you from doing so?

#include <fstream>
#include <string>

class IFStream
{
std::ifstream m_ifs;
public:
IFStream(std::string s_fn) : m_ifs(s_fn.c_str()) { }
~IFSTream() { }
...
};

int main()
{
std::string file("test.bin");
IFStream( file );
}
Oh yeah, good idea. But why use a c_str() with ifstream when it's so
simple to add an overloaded member function that takes a std::string?

But isn't it just as simple to use .c_str() ?

--
http://www.munted.org.uk

Take a nap, it saves lives.

[Alex Buell]

On Tue, 4 Apr 2006 03:33:15 -0700 "Jim Langston"
<ta*******@rocketmail.com> waved a wand and this message magically
appeared:

Oh yeah, good idea. But why use a c_str() with ifstream when it's so
simple to add an overloaded member function that takes a std::string?

But isn't it just as simple to use .c_str() ?

That's what I decided to do, in the end. It was the least ugly
solution.

--
http://www.munted.org.uk

Take a nap, it saves lives.

[mlimber]

Alex Buell wrote:

Why do I have to do the following if I want to open a file for reading
like
string filename = "data.txt";
ifstream ifs(filename.c_str());

I'd have thought that it would be quite elegant to do

ifstream ifs(filename);

instead!

That's an artifact of the developing C++ standard, unfortunately, but
it will almost certainly be corrected in the next revision of the
standard (sometimes called C++0x).

Cheers! --M