Re: Test Code for file not found in file I/O situations

HI dear,

I cant get your question very clearly. but as per my understanding I am
writing you the simple solution.

One thing you can do to check that whether a file already exists or not
is just open a file for reading . and if file open is successful then
file already exists. so you can close this file, display an error
message " File already exists..." and ask for other file name.

if the file could not be opened for reading then it means that there is
no already existing file with the same name. so you can now open this
file for writing and start writing into it.

instead of using system("Pause") to give a pause. you can use getch()
defoned in conio.h
( #include <conio.h>)

Hope it will solve your problem.

Best Regards,
BS.

Kris Thayer wrote:
> Hello,
> I'm in an Intro to Programming class with C++. I have this small project based on using c_str for I/O with files.
> Can someone help me with my attempt to check for whether the file exists and get it to work so the program doesnt' just close when a file that doesn't exist gets typed in? I'm using DevC++ so have to use system("PAUSE"); in the code.
>
> Here's the code:
>
> //****************** this line is 70 characters long **********
> #include <iostream>
> #include <string>
> #include <fstream>
> #include <cassert>
>
> /*
> Kris Thayer
> 10/3/05
> Assignment 5.5
>
> This program asks to enter the name of a file and then counts the
> words in the file. A word is any sequence of non-whitespace
> characters. When "quit" is entered, the program ends. The files must
> be located in the same folder as the project file. Data is input into
> the program one character at a time and keeps track of current and
> previous characters. Any time the previous character or current character
> is a whitespace character, there's an increment to the count.
> */
>
> using namespace std;
>
> int main()
> {
> char currentChar; // current character read in
> char previousChar; // last character read
> int wordCount; // count of sequences of non-whitepace
> string fileName; // name of file entered
> ifstream inFile; // declaration of a file variable
>
> cout << "Type in the filename: ";
> cin >> fileName;
>
> if (!inFile)
> {
> cout << "Please enter a filename that exists: " << endl;
> cin >> fileName;
> }
> while (fileName != "quit")
> {
>
> inFile.open(fileName.c_str());
> assert(inFile);
>
> wordCount = 0;
> inFile.get (previousChar);
> inFile.get (currentChar);
>
> while (inFile)
> {
> if ((previousChar != ' ' && previousChar != '\n') &&
> (currentChar == ' ' || currentChar == '\n'))
>
> wordCount++;
> previousChar = currentChar;
> inFile.get (currentChar);
> }
>
> if (previousChar != ' ' && previousChar != '\n')
>
> wordCount++;
>
> cout << "This file contains " << wordCount << " words." << endl;
>
> inFile.close();
> inFile.clear();
>
> cout << "\n" << endl;
> cout << "Type in another filename: ";
> cin >> fileName;
> }
> system ("pause");
>
> return 0;
> }
>
>
> Thanks
> Kris