i want to read a text file into an array of strings. this isn't possible, is it? i'm going to have to use characters instead? anyone have a suggestion?

Hold on a second, I'll cobble something together.

/* read_lines.cpp

 */



#include <stdio.h>

#include <string>

#include <vector>



int main(int argc, char *argv[])

{

	if (argc < 2)

	{

		fprintf(stderr, "Usage: read_lines filename\n");

		return 1;

	}



	FILE *fp = fopen(argv[1], "r");

	if (!fp)

	{

		fprintf(stderr, "Failed to open %s\n", argv[1]);

		return 2;

	}



	typedef std::vector< std::string > lines_t;

	lines_t lines;



	const size_t buffer_size = 1024;

	char *buffer = new char[buffer_size];



	std::string residue;



	while (!feof(fp) && !ferror(fp))

	{

		size_t bytes_read = fread(buffer, 1, buffer_size, fp);



		const char *buffer_end = buffer + bytes_read;

		

		const char *b = buffer;

		const char *e;

		while((e = (const char *)memchr(b, '\n', buffer_end - b)) != NULL)

		{

			std::string line(b, e);

			residue += line;

			lines.push_back(residue);

			residue.clear();



			b = e + 1;

		}



		// Is there any residue?

		if (b < buffer_end)

		{

			// There's some residue

			residue += std::string(b, buffer_end);

		}

	}



	if (!residue.empty())

		lines.push_back(residue);



	delete [] buffer;



	fclose(fp);



	int n = 0;

	for (lines_t::const_iterator i = lines.begin(); i != lines.end(); ++i)

	{

		++n;

		printf("%d: %s\n", n, i->c_str());

	}



	return 0;

}

And a quick description of how it works. The main body of the program reads the named file into a vector of strings.

It does this by allocating a buffer and reading the file into it until it runs out of file. For each buffer of data that it reads from the file, it looks through for line-breaks, using memchr.

Because the buffer might not finish with a complete line, we collect the last part of the buffer into a string called 'residue'. So we need to remember to keep it around for the start of the next buffer.

When we run out of file, we might still have some residue, so we add this to the vector as well.

Then, when we're done, we print out the vector to the screen.

Oh, my lord. Fifty-five lines just to read in a file line-by-line and print it back out! And people complain about C being too low-level.

cool. funny how i could understand what needs to happen much easier using c functions, when i was trying to do it with fstream and ending up with really jumbled up code. thanks roger.

Use delphi instead:

procedure ReadTextFile(AFile : String);

var

   SL : TStringList;

begin

      SL := TStringList.Create;

      try

         SL.LoadFromFile(AFile);    

        // strings are now in the stringlist object                    

     finally

         SL.Free;

     end;

end;

C'mon... be fair to Roger...he did print them back out...

Or Perl:

#!/usr/bin/perl



open F,"test.pl";@l=<F>;close F;print @l;

or Python:

f = file("file.txt", "r")

l = f.readlines()

f.close()

Or shell:

#/bin/sh

cat $MYFILE

#

julf - requirement was that it had to read the lines of the file into an array.

Have to use ksh. No lesser sh has arrays.

#!/usr/bin/ksh

exec 5<file.txt

set -A array

i=0

while read -ru5 array[$i]; do

        i=$(($i+1))

done



# And, to be complete

i=0

j=${#array[@]}

while [ $i -lt $j ]; do

        echo ${array[$i]}

        i=$(($i+1))

done

requirement was that it had to read the lines of the file into an array.

Duhh. Guess I should learn to read