c++ read from file question

[mordi05]

Hi.
I am quite new to c++, but I figured I'd like to learn it so I'm playing around with some things.

Currently I am trying to read from a text file with the following content:

"city1", "city2", "city3"...

i.e. a file with several strings in "" separated with commas. I would like to store each of these strings into a cell in an array. (Rewriting the text file format is out of the question, because really there are thousands of strings in it).

So far I am using this code:

ifstream inFile; // Declaring an input file stream (ifstream) variable.

inFile.open("/home/..../test2.txt");

if (!inFile) { // Checking that the file could be read
cerr << "Unable to open file test2.txt";
exit(1); // call system to stop
}

while (inFile >> x){ // read from the stream

}

inFile.close(); // Closing the input stream to free memory

Now, the problem is obviously the (inFile >>) command. I dont know how to use syntax so the that I load each string from the file into a separate array cell. All I have been able to do is load all the text in the textfile into a single variable at once. (of course, while using another, shorter textfile).

Any help is appreciated, thanks.

[LaRoza]

Any reason you are using C++? That is not the most useful language for text processing...

[mordi05]

Not for this, no.
I want to learn some c++, and this is just part of one of many different "problems" i found on a website.

[dempl_dempl]

while (   !inFile.eof()  ){ // read from the stream
inFile >> x;
}

You don't need the following :

inFile.close(); // Closing the input stream to free memory

ifstream destructor does the job when exiting from function.

You should get used to close files without close() method , for example in the stuff like try/catch blocks. But, don't worry about that for now , you'll see it yourself in practice .

[mordi05]

Thanks a lot. That gets me further.
But, should it not be ! inFile.eof() ?

This function reads one character at a time, right. I would like to be able to read an entire string at time. i.e first read out: "Washington", second read out: "Chicago" etc. They are separated with commas in the file.

If I'm missing something obvious, please bear with me.

[dempl_dempl]

Yeap, sorry, my bad .
I've corrected the post.


Show me the file.txt , the way it looks like .
(1) If the names are placed in sequence :
e.g. :

  Belgrade Washington Paris Moscow

You can do this:

string str;
ifstream fin ( "myfile");
while ( !fin.eof()  )
{
   fin >> str;
 /*do something usefull here :-)*/
}

In the case cities are separated by quotes and commas , I can give you this hint :
I believe you don't need commas when you have quotes, and you don't need quotes when you have commas , because both of them are good separators. I would use the commas or newlines ( "\n" )

I haven't checked the code, please post if you find something wrong . Spelling and grammar errors are exception .

Drop the file , the way it looks like, in order to give you precise instructions.

Cheers!

[mordi05]

"Kaneohe","Kapolei","Salt Lake","Ewa Beach","Manoa"

This is what the file looks like. And it goes on of course.

EDIT: And all the text is in one line.

[SledgeHammer_999]

look here for more info on I/O with C++ link.

If you try the above example then you will read the text file line-by-line. Each time you read a line into a "string" variable you should parse the string variable. Eg search the string for , and ".

More info for string's method here

[mordi05]

Thanks, I will definitely check that out.

I guess I was just hoping that since

char *cities[3]={"bergen","london","madrid"};

is a valid statement, and on the same format as my file, I could in a crude way get my file to be loaded as those initializers.

I'll get some sleep now, but if anyone has a great idea, I'd love to wake up to it.

[dempl_dempl]

Ok, I thought there were spaces between the cities.

Here's the code that will work:

#include <list>
#include <string>
#include <fstream>

using namespace std;

char ch;


ifstream fin ( " myfile.txt" );
list<string> cities;

string tmp_str;

while(  !fin.eof() ) 
{
 fin.read(&c,1);
 
 if( c == ',') 
 {
   tmp_str.erase( tmp_str.begin() ) ; // erase the first character ( the opening quote )
   tmp_str.erase( tmp_str.end() ) ; // erase the lase character ( the closing quote )

   cities.push_back(  tmp_str );
   tmp_str.clear();
   
 }

tmp_str = tmp_str + c;

}

Example usage of those strings :

for(  list< string >::iterator  ii = cities.begin() ; ii != cities.end() ; ii++ )
  cout << *ii  << endl; // print the current city