Programming Forums > Application Development > C++

KTiger · May 11th, 2006, 5:55 PM

Hi!
I have used VB6 for years and resently moved to Gambas (linux-version of VB), and I have some trouble too learn C++,

why isn't there any simple examples on this in linux,, ie. "man fopen" does not give me any examples :mad: (I really liked the old QBasic help system, is there some for C++?)

In VB6 I could write a file with doing follow:

(Toggle Plain Text)

  string myfile;
  string temp;

  open myfile on #1 for input     // something like that... its a while since I have used VB.
  while not eof(1)
  (
    input line #1, temp
    print temp;
  )
  close #1

how is this done in C++ (G++ actually), to read line by line, and print it to the screen.
I have managed to do this:

(Toggle Plain Text)

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
  char string1[20], string2[20], string3[30];
  ifstream fin("file.dat");

  if (!fin.is_open()) {
    cerr << "Error: Could not open file." << endl;
    exit(1);
  }

  fin >> string1;
  fin >> string2;
  fin >> string3;

  cout << string1 << " " << string2 << " " << string3 << endl;

  fin.close();

  return 0;
}

but this does not give me a loop to cycle through the file, plus it seems to remove some spesial chars like "\n" why?
And still I got alot of other questions, but those I'll take later.

plz, forgive me if there some english errors..

DaWei · May 11th, 2006, 6:19 PM

Google. You'll be inundated. You can also search THIS forum for links. You may not find anything specific to fopen, but you'll find plenty of links to good tutorials. Loops are control constructs; one places them wherever one needs repetetive operations. They aren't restricted to file operations, but come in handy there, as well. There are many input and output functions over and above the insertion and extraction operators (<< and >>). Why? Because they don't serve all purposes well. Pick and choose, just as you do on the candy aisle (or, at least, I do). Read the documentation for what you pick. Find how it informs you of failure and be sure to ask it.

Jimbo · May 11th, 2006, 7:41 PM

Quote:

Originally Posted by KTiger

how is this done in C++ (G++ actually), to read line by line, and print it to the screen.

C++ is the language, g++ is a compiler.

Prm753 · May 11th, 2006, 10:47 PM

Did you take a look at this:

http://www.cs.odu.edu/~jbollen/CS149.../cpp_files.pdf

This is quite informative about fin and fout.

nnxion · May 12th, 2006, 5:27 AM

fopen is C. Using the ifstream constructor is C++.
Do you want something like:

(Toggle Plain Text)

#include <iostream>
#include <string>
#include <fstream>
using namespace std;

int main()
{
	string string1, string2, string3;
	ifstream fin("file.dat");

	if (!fin.is_open())
	{
		cerr << "Error: Could not open file." << endl;
		exit(1);
	}

	getline(fin, string1);
	getline(fin, string2);
	getline(fin, string3);

	cout << string1 << endl << string2 << endl << string3 << endl;

	fin.close();

	return 0;
}

KTiger · May 12th, 2006, 7:17 AM

Wow, so many responses in soo little time... (I'll stick to this forum from now on)

Thanks nnxion, getline is what I have been searching for along time.
Now I need to figure out how to read through any file, since I dont know how to detect the EOF.
( The final idea is to read the entire file in to a string[] , so I can make a very simple editor)

Jimbo:

(Toggle Plain Text)

C++ is the language, g++ is a compiler.

Jimbo your right, I dont know why I'd mixed them. :o

DaWei · May 12th, 2006, 7:20 AM

READ your documentation. If you don't know how to detect EOF, it's clear you haven't.

nnxion · May 12th, 2006, 7:50 AM

Quote:

Originally Posted by DaWei

READ your documentation. If you don't know how to detect EOF, it's clear you haven't.

As DaWei says, it's important to read your documentation. If you don't have money to buy a book it's probably a good idea to read a tutorial, like here.

Try to do the best you can and try examples out on your compiler, learn to use the debugger, he's among my best friends when it comes to programming. (That's just an expression, if you're worried

)

If you're still stuck at that point, then come to us and ask us for help.

May 11th, 2006, 6:19 PM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Google. You'll be inundated. You can also search THIS forum for links. You may not find anything specific to fopen, but you'll find plenty of links to good tutorials. Loops are control constructs; one places them wherever one needs repetetive operations. They aren't restricted to file operations, but come in handy there, as well. There are many input and output functions over and above the insertion and extraction operators (<< and >>). Why? Because they don't serve all purposes well. Pick and choose, just as you do on the candy aisle (or, at least, I do). Read the documentation for what you pick. Find how it informs you of failure and be sure to ask it. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

May 11th, 2006, 10:47 PM	#4
Prm753 Professional Programmer Join Date: Oct 2005 Location: United States Posts: 447 Rep Power: 4	Did you take a look at this: http://www.cs.odu.edu/~jbollen/CS149.../cpp_files.pdf This is quite informative about fin and fout. __________________ The world's first athletic computer geek! The home of PrProgramsStudios How not to post a question: <-- Please don't reply

May 12th, 2006, 5:27 AM	#5
nnxion Programming Guru Join Date: Jun 2005 Location: elemental plane Posts: 1,429 Rep Power: 5	fopen is C. Using the ifstream constructor is C++. Do you want something like: (Toggle Plain Text) #include <iostream> #include <string> #include <fstream> using namespace std; int main() { string string1, string2, string3; ifstream fin("file.dat"); if (!fin.is_open()) { cerr << "Error: Could not open file." << endl; exit(1); } getline(fin, string1); getline(fin, string2); getline(fin, string3); cout << string1 << endl << string2 << endl << string3 << endl; fin.close(); return 0; } #include <iostream> #include <string> #include <fstream> using namespace std; int main() { string string1, string2, string3; ifstream fin("file.dat"); if (!fin.is_open()) { cerr << "Error: Could not open file." << endl; exit(1); } getline(fin, string1); getline(fin, string2); getline(fin, string3); cout << string1 << endl << string2 << endl << string3 << endl; fin.close(); return 0; } __________________ "Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for." -- Socrates

May 12th, 2006, 7:17 AM	#6
KTiger Newbie Join Date: May 2006 Location: Narvik, Norway Posts: 22 Rep Power: 0	Wow, so many responses in soo little time... (I'll stick to this forum from now on) Thanks nnxion, getline is what I have been searching for along time. Now I need to figure out how to read through any file, since I dont know how to detect the EOF. ( The final idea is to read the entire file in to a string[] , so I can make a very simple editor) Jimbo: (Toggle Plain Text) C++ is the language, g++ is a compiler. C++ is the language, g++ is a compiler. Jimbo your right, I dont know why I'd mixed them. :o

May 12th, 2006, 7:20 AM	#7
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	READ your documentation. If you don't know how to detect EOF, it's clear you haven't. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

May 11th, 2006, 5:55 PM	#1
KTiger Newbie Join Date: May 2006 Location: Narvik, Norway Posts: 22 Rep Power: 0	C++ examples Hi! I have used VB6 for years and resently moved to Gambas (linux-version of VB), and I have some trouble too learn C++, why isn't there any simple examples on this in linux,, ie. "man fopen" does not give me any examples :mad: (I really liked the old QBasic help system, is there some for C++?) In VB6 I could write a file with doing follow: (Toggle Plain Text) string myfile; string temp; open myfile on #1 for input // something like that... its a while since I have used VB. while not eof(1) ( input line #1, temp print temp; ) close #1 string myfile; string temp; open myfile on #1 for input // something like that... its a while since I have used VB. while not eof(1) ( input line #1, temp print temp; ) close #1 how is this done in C++ (G++ actually), to read line by line, and print it to the screen. I have managed to do this: (Toggle Plain Text) #include <iostream> #include <fstream> using namespace std; int main() { char string1[20], string2[20], string3[30]; ifstream fin("file.dat"); if (!fin.is_open()) { cerr << "Error: Could not open file." << endl; exit(1); } fin >> string1; fin >> string2; fin >> string3; cout << string1 << " " << string2 << " " << string3 << endl; fin.close(); return 0; } #include <iostream> #include <fstream> using namespace std; int main() { char string1[20], string2[20], string3[30]; ifstream fin("file.dat"); if (!fin.is_open()) { cerr << "Error: Could not open file." << endl; exit(1); } fin >> string1; fin >> string2; fin >> string3; cout << string1 << " " << string2 << " " << string3 << endl; fin.close(); return 0; } but this does not give me a loop to cycle through the file, plus it seems to remove some spesial chars like "\n" why? And still I got alot of other questions, but those I'll take later. plz, forgive me if there some english errors..

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Programming Forums > Application Development > C++

C++ examples