C
Cheryl
how can i read a string from a text file in c++ using fstream.h?
e.g.
in the text file
e.g.
in the text file
C
Chris Theis
Why do you want to read it as a char array? You're far better of reading itCheryl said:
as a string because you don't need to know in advance how many characters
you're going to read. Afterwards you can still assign it to a char array if
you want/need to.
string MyString;
FileStream >> MyString;
In case you want to read a whole line of words that are delimited by spaces
you might consider using the getline function. Anyway, look up streams in
any decent C++ beginner's book.
Chris
R
Rolf Magnus
Cheryl said:
What do you want to read into the string? A line? Part of a line? The
whole file?
Anyway, I'd recomment using the standard streams from <fstream> instead
of the non-standard said:
And here, I'd recomment using std::string instead of char arrays.
#include <fstream>
#include <string>
#include <iostream>
int main()
{
using namespace std;
ifstream file("file.txt");
string line;
while (getline(file, line))
cout << line << endl;
}
K
Karl Heinz Buchegger
osmium said:
Even then std::string would be a better choice
Unless, of course, the assignment asks for a solution using a character array.
O
osmium
Chris said:
Perhaps she didn't write the file? It seems quite plausible that the
instructor provided a file.
Cheryl: std::istream::get() will read a character at a time. Keep looking
for a terminating '\0' and buffer overflows. This will be quite inefficient
due to large numbers of functions calls, but it should be good enough for
your current problem.
C
Chris Theis
osmium said:
Sorry, I may be a little thick today but what does it matter who created the
file? AFAIK the choice of string or char array is independent of the creator
of the file, but probably I might be mistaken here...
Chri
H
Howard
I think you are not grasping the concept of reading into the string class
via a stream. Doing it this way allows you to read data in just as it would
when reading into a char array, but the string class provides better
control, ease of use, and more functionality. It's not that you're loading
a persisted structure from the file, it's that you're reading in characters
(or lines of characters) into a string variable, which handles the dirty
work for you. It's much easier and cleaner!
-Howard
J
Jay O'Connor
Chris said:
Sorry, I may be a little thick today but what does it matter who created the
file? AFAIK the choice of string or char array is independent of the creator
of the file, but probably I might be mistaken here...
If the instructor created the file, that means it's an assignment of
some sort, in which case their may be requirements in the assignment to
use a char array rather than a string, depending on what is being taught.
Take care,
Jay
O
osmium
Karl said:osmium said:
Even then std::string would be a better choice
It seems to me that would violate a cardinal rule of object oriented
programming. There should be no way for the user of a class to determine
the methods of representation of that class, either in RAM or on mass
storage. It should be assumed that there is an unknowable "blob" on the
storage medium. I don't know how strings are stored, I don't want to know
and I shouldn't know - no one should tell me. I see no difference between
this proposal and "knowing" that the mouse x-y coordinates are always at
location such and such.
Or are you suggesting that the instructor goofed?
C
Cheryl
problem solved
thx
thx
Rolf Magnus said:
C
Chris Theis
osmium said:Karl said:osmium said:
Even then std::string would be a better choice
It seems to me that would violate a cardinal rule of object oriented
programming. There should be no way for the user of a class to determine
the methods of representation of that class, either in RAM or on mass
storage. It should be assumed that there is an unknowable "blob" on the
storage medium. I don't know how strings are stored, I don't want to know
and I shouldn't know - no one should tell me. I see no difference between
this proposal and "knowing" that the mouse x-y coordinates are always at
location such and such.
Whoa, relax pal! We're talking about the simple problem to read a string or
text from a file. This is not about persistency or any other sophisticated
concept. Furthermore even if you assume that an unknowable "blob" is stored
on the medium you'll first have to get some information what that blob is,
trigger for example a generic factory and tell the spawned object to read
itself in. Thus, without any knowledge nothing is possible. The statement
that using a string class or "knowing" that the mou x-y coordinates are
always at location such and such is way out of line. Using the string class
you do not have to know anything about its internal representation, the only
thing you have to know is that you expect a string. The solution reading a
text character by character is extremely tedious and error prone and IMHO
should only be resorted to, if there are good reasons for that.
No, Karl Heinz did not suggest that the instructor goofed and neither did I.
Though there are some instructors that should certainly catch up on their
C++ knowledge (which is just a general comment and opinion of myself!)
Regards
Chris