Thread: Opening User Specified Files in C

Hello,

I'm having a bit of trouble opening a user specified file in C. When I execute my code, it will not open the file, even though the files are in the same directory. I have even added them under the Resources folder.

I'm working in Visual Studio 2010. I remember someone told me I had to change some settings for it work, but I cannot remember what it was. The settings are default.

Anyway here's my code:

Code:

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>



int main()
{

	char fname[10]; //spreadsheet 

	printf("Please enter the name of the SPREADSHEET you want to use: ");
	fflush(stdin);
	gets(fname);

	FILE *fp;
	if ((fp=fopen(fname, "r")) == NULL)
	{
		printf("\nCannot open file");
		getch();
		exit(1);
	}
	
	fclose(fp);


	return 0;
}

Any help would greatly be appreciated. If you've had this problem before, and even the slightest adjustment made it work, please share it! Thanks.

Code:

fflush(stdin);
gets(fname);

For starters you should not be using either of these!
Cprogramming.com FAQ
Cprogramming.com FAQ

Next, is the file in the same directory as the one you're running the executable from?

Code:

fflush(stdin);

Bad! Read Cprogramming.com FAQ > Why fflush(stdin) is wrong and Cprogramming.com FAQ > Flush the input buffer.

Code:

gets(fname);

Bad! Read Cprogramming.com FAQ > Why gets() is bad / Buffer Overflows.

Try printing a more useful error message, that actually says why you couldn't open the file. Look up the perror function, or use errno and strerror. Just remember to #include <errno.h>.

Okay okay, I got it the first time haha.

Yes, the files are all in the same directory. I've tested a similar code that my friend made although his was "hard coded" and his works just fine.

Originally Posted by CommonTater

On modern machines you should probably be using something like char fname[255]; ... no kidding I've seen file paths 3 and 4 lines long and they're not at all uncommon on poorly organized systems. The odds are that, as the others have pointed out, your filename is being clipped to 9 characters...

You were given good advice in several ways by CommonTater.

If using a C99 compatible compiler, consider using: char fname[FILENAME_MAX];

FILENAME_MAX is defined in the <stdio.h> and is defined for the longest filename that an implentation will open.

I do not have a copy of the C90 standard to determine if this macro was defined in <stdio.h> in that version of the language standard also.

The files are in the same directory, but that doesn't mean that you are in that directory (and, in fact, the evidence suggests you are not). Either move the files to the directory you are in or move yourself to the directory the files are in, or just specify the full path. (If you don't know where you are, then maybe _getcwd() is for you.)

Nope, still nothing.

I'm not sure how to use the _getcwd() command.

I am on a Windows machine, and the fact that I do not know is because I've only taken a Intro to C, class. Where this is one part of the assignment. However I can't get it to work at all. We're only limited to what we've learned. Everything mentioned here is new to me.

So if you could all elaborate a bit more, that would be GREATLY appreciated.

Originally Posted by Pztar

Nope, still nothing.

I'm not sure how to use the _getcwd() command.

I am on a Windows machine, and the fact that I do not know is because I've only taken a Intro to C, class. Where this is one part of the assignment. However I can't get it to work at all. We're only limited to what we've learned. Everything mentioned here is new to me.

So if you could all elaborate a bit more, that would be GREATLY appreciated.

Change the setting in Windows... that has nothing to do with your class or C ... it's just Microsoft being stupid.

What you may discover is that you have a hidden second extension on the filename... it happens a lot.

When you run a program, you start in ... some directory. Generally that directory is not where the executable lives, but rather what directory you are in when you run the program. For instance, if I am in C:\ and type "notepad" then my working directory will be C:\, because that's where I was when I started the program, as opposed to ... whatever directory notepad.exe lives in.

Since you are relying on the IDE to start your program, then the IDE is setting the current working directory somewhere. You should either change it to the directory you want it to be, or at the very least figure out what it is so that you can move your file there, or (and this is something we should have started with) make sure you are actually getting the filename you expect, perhaps by printing it out to verify.

Originally Posted by Pztar

I really don't know what I'm doing wrong. I set my files in my same folder where the vcxproj file is. It just won't open no matter what I do.

CommonTater: I did what you said, it didn't work.

ImageShack® - Online Photo and Video Hosting

That's what my directory looks like. Everything is in there.

Everything is in there ... except your program itself, which is in the Debug folder. Did you try moving your text file there? (Not that that's a guarantee of anything, but at least it's somewhere new to try.)

Yes, I just tried that. I realized when I debug it says
ignment3.exe': Loaded 'C:\Users\P\Desktop\Assignment3\Debug\Assignment3. exe', Symbols loaded.

So i thought I'd put the files in the Debug folder, however that didn't change anything. It can't be anything complicated. I just don't know what it is.

Originally Posted by Pztar

I really don't know what I'm doing wrong. I set my files in my same folder where the vcxproj file is. It just won't open no matter what I do.

CommonTater: I did what you said, it didn't work.

ImageShack® - Online Photo and Video Hosting

That's what my directory looks like. Everything is in there.

Yes... everything except the executable... move your txt files to the debug directory, where the executable file is or specify ..\filename.ext when entering your filenames...

And don't undo that windows change. Seriously, you'll find it a big help everywhere...