Programming Forums > Application Development > C++

tayspen · May 14th, 2006, 8:59 PM

Ok, I need to make a program that will firt, check if a files exists, and if it does, list it.

Then another part of the program needs to delete it. This is what I have for that.

(Toggle Plain Text)

switch (c)
     {
        case '1' :  
        cout << "Scanning for files...";
        remove("C:\\mydata.txt");	
        break;
     }

Is that the best way to delete a file? And how can i check if it exists?

Prm753 · May 14th, 2006, 9:24 PM

How 'bout something like:

(Toggle Plain Text)

#include <iostream>
#include <fstream>

using namespace std;
int main()
{
    ifstream fin("C:\\mydata.txt");
    if (fin)
    {
       cout << "File found, deleting..." << endl;
       system("DEL /F C:\\mydata.txt");
       fin.close();
    }
    else
    {
       cout << "Could not find file!" << endl;
    }
    cin.get(); 
    return 0;
}

Will that work?

As to remove(), I have only used it some, but I like DeleteFile(); better. System(DEL "myfile.txt"); works if you have Windows, but is not portable.

tayspen · May 14th, 2006, 9:34 PM

Thanks

.

Jimbo · May 14th, 2006, 9:47 PM

I think remove() comes in cstdio, in which case you could just use it for the deletion. It is probably the easiest way to delete the file. To see if a file exists, you can try to create an fstream to it using the ios::nocreate flag, and if the process fails the file does not exist. However, putting these two together is mixing C and C++ file I/O. You can use FILE* fopen(const char*, const char*) with the file name and "r" instead. This is the C way of opening a file, and if the function returns a null pointer, then the file didnt exist (or you may have permissions errors).

Prm753 · May 14th, 2006, 10:38 PM

Hey tayspen,

I mistyped something in that code sample:

(Toggle Plain Text)

if (fin)
{
     cout << "File found, deleting..." << endl;
     system("DEL /F C:\\mydata.txt");
     fin.close();
}

should be

(Toggle Plain Text)

if (fin)
{
       cout << "File found, deleting..." << endl;
       fin.close();
       system("DEL /F C:\\mydata.txt");
}

Sorry about that.

nnxion · May 15th, 2006, 5:00 AM

Quote:

Originally Posted by Jimbo

To see if a file exists, you can try to create an fstream to it using the ios::nocreate flag, and if the process fails the file does not exist.

I'm sorry to tell you, but ios::nocreate hasn't made it to the C++ standard.

me22irc · May 15th, 2006, 4:47 PM

Quote:

Originally Posted by Prm753

Hey tayspen,

I mistyped something in that code sample:

(Toggle Plain Text)

if (fin)
{
     cout << "File found, deleting..." << endl;
     system("DEL /F C:\\mydata.txt");
     fin.close();
}

should be

(Toggle Plain Text)

if (fin)
{
       cout << "File found, deleting..." << endl;
       fin.close();
       system("DEL /F C:\\mydata.txt");
}

Sorry about that.

Thanks, I figured it out

May 14th, 2006, 8:59 PM	#1
tayspen Hobbyist Programmer Join Date: Sep 2005 Location: A House... Posts: 191 Rep Power: 4	Check if file exists, and delete file Ok, I need to make a program that will firt, check if a files exists, and if it does, list it. Then another part of the program needs to delete it. This is what I have for that. (Toggle Plain Text) switch (c) { case '1' : cout << "Scanning for files..."; remove("C:\\mydata.txt"); break; } switch (c) { case '1' : cout << "Scanning for files..."; remove("C:\\mydata.txt"); break; } Is that the best way to delete a file? And how can i check if it exists? __________________ ManagePod, an iPod Management tool. - Forums Gaming Forums. Tough Admin

May 14th, 2006, 9:24 PM	#2
Prm753 Professional Programmer Join Date: Oct 2005 Location: United States Posts: 447 Rep Power: 4	How 'bout something like: (Toggle Plain Text) #include <iostream> #include <fstream> using namespace std; int main() { ifstream fin("C:\\mydata.txt"); if (fin) { cout << "File found, deleting..." << endl; system("DEL /F C:\\mydata.txt"); fin.close(); } else { cout << "Could not find file!" << endl; } cin.get(); return 0; } #include <iostream> #include <fstream> using namespace std; int main() { ifstream fin("C:\\mydata.txt"); if (fin) { cout << "File found, deleting..." << endl; system("DEL /F C:\\mydata.txt"); fin.close(); } else { cout << "Could not find file!" << endl; } cin.get(); return 0; } Will that work? As to remove(), I have only used it some, but I like DeleteFile(); better. System(DEL "myfile.txt"); works if you have Windows, but is not portable. __________________ The world's first athletic computer geek! The home of PrProgramsStudios How not to post a question: <-- Please don't reply

May 14th, 2006, 9:34 PM	#3
tayspen Hobbyist Programmer Join Date: Sep 2005 Location: A House... Posts: 191 Rep Power: 4	Thanks . __________________ ManagePod, an iPod Management tool. - Forums Gaming Forums. Tough Admin

May 14th, 2006, 10:38 PM	#5
Prm753 Professional Programmer Join Date: Oct 2005 Location: United States Posts: 447 Rep Power: 4	Hey tayspen, I mistyped something in that code sample: (Toggle Plain Text) if (fin) { cout << "File found, deleting..." << endl; system("DEL /F C:\\mydata.txt"); fin.close(); } if (fin) { cout << "File found, deleting..." << endl; system("DEL /F C:\\mydata.txt"); fin.close(); } should be (Toggle Plain Text) if (fin) { cout << "File found, deleting..." << endl; fin.close(); system("DEL /F C:\\mydata.txt"); } if (fin) { cout << "File found, deleting..." << endl; fin.close(); system("DEL /F C:\\mydata.txt"); } Sorry about that. __________________ The world's first athletic computer geek! The home of PrProgramsStudios How not to post a question: <-- Please don't reply

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May 14th, 2006, 9:47 PM	#4
Jimbo Battle Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 769 Rep Power: 3	I think remove() comes in cstdio, in which case you could just use it for the deletion. It is probably the easiest way to delete the file. To see if a file exists, you can try to create an fstream to it using the ios::nocreate flag, and if the process fails the file does not exist. However, putting these two together is mixing C and C++ file I/O. You can use FILE* fopen(const char, const char) with the file name and "r" instead. This is the C way of opening a file, and if the function returns a null pointer, then the file didnt exist (or you may have permissions errors).

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Programming Forums > Application Development > C++

Check if file exists, and delete file