Can someone who knows C++....

[TheLinuxDuck]

Help me with a dilemma??

I'm looking for info on using the string class. I was writing a c++ file copy utility (to learn) and was forced to use a char*.

I'd rather not, since that type of variable kinda defeats the purpose of OOD.

Can someone show me how to read a line of text or data from a file, and store it into a string variable?

I would greatly appreciate! (and I'll prolly put the example on the CCAE site, too)

[Bradmont]

The functions are:


getline(istream & in, string & foo)
getline(istream& in, string & foo, char terminatingcharacter)


terminatingcharacter defaults to a newline, but u can use anything else.

Use them like this:

ifstream in; //open it and stuff, can use any istream
string foo;
getline(in, foo); // gets a whole line up to a '\n'
getline(in, foo, '_'); //gets everything up to the next "_"


<edit> I guess it would make sense to use code tags her... :rolleyes:</edit>

<edit> Bah, I suck. This is the last time I'll edit it... no, really... </edit>

[ 24 April 2001: Message edited by: Blargmont ]

[TheLinuxDuck]

Blargmont:

Does that version of getline leave the terminating character on the read line, or does it remove it, like the ifstream getline does?

Does that getline have a max length of how many chars it will read at a time? Will string will itself up no matter (memory willing)?

Thanks for the info though, it looks like that's going to be the thing I need.. (^:

[Bradmont]

It does strip the terminating character. I don't know if it has any size limit. I don't think it does (but it'd be pretty easy to test ;))

[ 24 April 2001: Message edited by: Blargmont ]

[Stuka]

Interesting question here Bradmont - is that getline a nonstandard extension? I can't find any reference to it in M$VC++ 6.0 (I know, I know :)). However, there are some interesting classes (istrstream, istringstream) that I'm trying to figure out how to use them now...

[TheLinuxDuck]

Rock on! I like things that I like, like that.

Btw, do they update gcount, as well?

[TheLinuxDuck]

For information's sake, I found out something poking around in the bastring.h file..

If you have a string class, and need to access it as a char *, you can simply say (example):


ifstream inFileStream(filename.data());


The data() function member of the string class returns a pointer to the actual data of the string class.. as it implies.. (^: very qool.. I was needing a way to do that, and voila, there it is!!

Thanks for the help, blarg!! (^: C++ isn't my greatest programming skill.. but I think I'd like to get into it some more...

Peace!

[lazy_cod3R]

i also think you can do

string theString="a_string";
then do

theString.c_str() to return a pointer to the actual char* its self.

[Bradmont2]

I'm pretty sure .data() and .c_str() do exactly the same thing.

And I'm pretty sure getline is standard, I know it works in VC++ 6 and GCC... its either in string or iostream, not sure which...

[Strike]

It's in iostream because it's a member of the cin iostream. cin.getline does the same thing, just assuring that it's from STDIN (unless cin can be redefined, and I forget if it can ... other than through redirection of course)

[Stuka]

Strike, Blarg(Brad, Brad2? :)),
I know getline is in there, but when I tried to use it (like your example there), I get invalid parameter errors for the string arguments...any hints?