In article <11************ **********@l41g 2000cwc.googleg roups.com>,
KL <kl*******@aol. com> wrote:
[...] I have a
.txt file that I want to read into a multi-dimensional string array.
Each line of the file needs to be read into the array.
Oh dear. Let me guess... each line of the file contains one question, and
you're supposed to set up a two-dimensional array of *characters* where
each "row" stores one question?
OK..sounds easy
enough, but I can't get the getline(file_na me array_name) to work.
Unfortunately, you've got more problems than just the getline(), if my
guess as to your task is correct. Dealing with character strings as
arrays of characters, and with collections of strings as two-dimensional
arrays of characters, is actually rather tricky and error-prone.
I'm not going to help you with doing it that way, because I wouldn't do it
that way even if someone held a gun to my head. C++ provides much better
tools for this, for six or seven years now, and instructors should not be
foisting the old methods on beginning students. Real programmers do need
to deal with this stuff in old code, but IMHO students should get a firm
grasp of the modern methods first.
Anyway, I'll content myself with presenting a modern C++ solution to your
problem, so you can compare it with the character-array solution when you
finally get it working, and hopefully you'll ask your school why your
instructor isn't staying up to date.
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;
int main ()
{
//-- 'string' is the standard C++ data type for storing character
//-- strings. It is provided for you via the <string> header. It is
//-- much nicer than an array of char for storing character strings,
//-- because it automatically grows or shrinks according to how many
//-- characters it needs to accommodate, so you don't declare it with
//-- a specific size, and you don't have to worry about overflowing it.
string line; // for holding each line in turn as we read it
//-- 'vector' is a standard C++ "container" which is similar to an array,
//-- but is nicer in many ways. For example, you can add data to it in
//-- such a way that it automatically expands as necessary; unlike an
//-- array, where you have to anticipate the amount of data it will need
//-- to store, and declare it with that specific size.
//-- You can declare a vector to have a specific size initially, but here
//-- we don't know how many items we're going to put in it, so we'll let
//-- it have zero size initially and let it expand as necessary.
vector<string> questions;
ifstream questionFile;
questionFile.op en ("qs.txt");
//-- All C++ input operations, including getline(), can be used as a loop
//-- condition; if the input succeeds, getline() evaluates as 'true' in
//-- the context of the 'while' statement, and you enter or continue the
//-- loop. If the input fails, getline() evaluates as 'false' and the
//-- loop terminates.
//-- Inside the loop, we take the line that we just read from the file,
//-- and use the vector's push_back() member function to append it to the
//-- end. The vector automatically "grows" as necessary.
while (getline (questionFile, line))
{
questions.push_ back (line);
}
questionFile.cl ose();
//-- A vector's size() member function tells us how many items it contains.
for (int k = 0; k < questions.size( ); ++k)
{
cout << questions[k] << endl;
}
return 0;
}
--
Jon Bell <jt****@presby. edu> Presbyterian College
Dept. of Physics and Computer Science Clinton, South Carolina USA
