Programming Forums > Application Development > C++

Cipher · Jun 15th, 2005, 4:42 PM

Ok I was reading "Sams: Teach yourself C++ in 21 Days" blah blah blah and I came across the section about using streams to read files. Soon after, I coded a CONSOLE(MS-DOS) Program to read a text file that I had typed. Here was the code in the book for reading files:

(Toggle Plain Text)

  #include<iostream>
  #include<fstream>
  using namespace std;
  int main()
  {
  	char filename[80];
  	cout << "enter filename where txt file is kept.";
  	cin >> filename:
  	ifstream fin(filename);
  	cout << "File Contents:  "
  	char ch;
  	while (fin.get(ch)) /*Problem begins here..../*
  		cout << ch;
  	cout << "\n END OF FILE REACHED\n";
  	fin.close();
  	return 0;
  }

I enter the file name. Which would be "C:\Documents and settings\Cipher\My Documents\My txt\Weapons List.txt" and
then it justs displays a blank line and "END OF FILE REACHED" then closes when I press enter? So I suppose it's not reading the file contents, did I just miss something such as a syntax error or do I maybe have to specify the text file itself?

Any help would be apperciated.

DaWei · Jun 15th, 2005, 5:07 PM

One possibility is that the file didn't open for any number of reasons. Actually, that's why they provide tests for that eventuality. Presuming that everything is going to work (including user input always being valid) is a serious mistake often made by beginners. It's something to get over as rapidly as you can if professional coding is your goal.

uman · Jun 15th, 2005, 5:09 PM

Are you sure you entered a valid path?

Ancient Dragon · Jun 15th, 2005, 5:19 PM

Quote:

Originally Posted by Cipher

Which would be "C:\Documents and settings\Cipher\My Documents\My txt\Weapons List.txt"

That string contains one or more spaces. Therefore you can't use cin's >> operator. use getline()

(Toggle Plain Text)

cin.getline(filename,sizeof(filename));

uman · Jun 15th, 2005, 5:58 PM

lol... we are dumb. I can't believe I didn't catch that

Scorpions4ever · Jun 15th, 2005, 6:01 PM

or use the string class and getline like this:

(Toggle Plain Text)

string filename;
getline(cin, filename);
ifstream fin(filename.c_str());

kurifu · Jun 15th, 2005, 9:17 PM

You could have caught that bug by using your IDE's debugging and analysis tools

would have saved you some time in awaiting an answer.

DaWei · Jun 15th, 2005, 9:37 PM

As a matter of fact, virtually all your code will be rife with information. In addition to the values in many of your variables, which you may inspect with a debugger or with something like an output statement, there are function returns and status queries which may be (and usually SHOULD be) examined. As I've said many times before, 99 point umpty-ump percent of the functions you use do not promise to deliver the goods. They promise to deliver the goods OR TELL YOU THAT THEY DID NOT. Be sure and ask them.

Jun 15th, 2005, 4:42 PM	#1
Cipher Hobbyist Programmer Join Date: Feb 2005 Location: /home/cipher Posts: 123 Rep Power: 4	Using Fstream to read files Ok I was reading "Sams: Teach yourself C++ in 21 Days" blah blah blah and I came across the section about using streams to read files. Soon after, I coded a CONSOLE(MS-DOS) Program to read a text file that I had typed. Here was the code in the book for reading files: (Toggle Plain Text) #include<iostream> #include<fstream> using namespace std; int main() { char filename[80]; cout << "enter filename where txt file is kept."; cin >> filename: ifstream fin(filename); cout << "File Contents: " char ch; while (fin.get(ch)) /Problem begins here..../ cout << ch; cout << "\n END OF FILE REACHED\n"; fin.close(); return 0; } #include<iostream> #include<fstream> using namespace std; int main() { char filename[80]; cout << "enter filename where txt file is kept."; cin >> filename: ifstream fin(filename); cout << "File Contents: " char ch; while (fin.get(ch)) /Problem begins here..../ cout << ch; cout << "\n END OF FILE REACHED\n"; fin.close(); return 0; } I enter the file name. Which would be "C:\Documents and settings\Cipher\My Documents\My txt\Weapons List.txt" and then it justs displays a blank line and "END OF FILE REACHED" then closes when I press enter? So I suppose it's not reading the file contents, did I just miss something such as a syntax error or do I maybe have to specify the text file itself? Any help would be apperciated. __________________ And there was much rejoicing... Yay....

Jun 15th, 2005, 5:07 PM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	One possibility is that the file didn't open for any number of reasons. Actually, that's why they provide tests for that eventuality. Presuming that everything is going to work (including user input always being valid) is a serious mistake often made by beginners. It's something to get over as rapidly as you can if professional coding is your goal. __________________ 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

Jun 15th, 2005, 6:01 PM	#6
Scorpions4ever Programmer Join Date: Jun 2005 Posts: 86 Rep Power: 4	or use the string class and getline like this: (Toggle Plain Text) string filename; getline(cin, filename); ifstream fin(filename.c_str()); string filename; getline(cin, filename); ifstream fin(filename.c_str());

Jun 15th, 2005, 9:17 PM	#7
kurifu Expert Programmer Join Date: Jul 2004 Location: Halifax, Nova Scotia (Canada) Posts: 784 Rep Power: 5	You could have caught that bug by using your IDE's debugging and analysis tools would have saved you some time in awaiting an answer. __________________ Clifford Matthew Roche <geek@cliffordroche.com> Web Hosting: http://www.crd-hosting.com Consulting: http://www.crdev-consulting.com

Jun 15th, 2005, 9:37 PM	#8
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	As a matter of fact, virtually all your code will be rife with information. In addition to the values in many of your variables, which you may inspect with a debugger or with something like an output statement, there are function returns and status queries which may be (and usually SHOULD be) examined. As I've said many times before, 99 point umpty-ump percent of the functions you use do not promise to deliver the goods. They promise to deliver the goods OR TELL YOU THAT THEY DID NOT. Be sure and ask them. __________________ 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

Jun 15th, 2005, 5:09 PM	#3
uman Expert Programmer Join Date: Dec 2004 Posts: 794 Rep Power: 4	Are you sure you entered a valid path?

Jun 15th, 2005, 5:58 PM	#5
uman Expert Programmer Join Date: Dec 2004 Posts: 794 Rep Power: 4	lol... we are dumb. I can't believe I didn't catch that

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++

Using Fstream to read files