Networks Project fopen (input filename)

TaiL · 07-08-2009, 04:38 PM

Hi there sorry if this is a repost, I am in a networking course and have a question (with many more to come).

First off a little bit about the proj, its an FTP stop and wait program.
As of right now I have created the sockets and have been able to connect and send txt. No I am trying to send data. My first step is taken a file name inputted by the user. Question is do i ask for filename or filepath

Code:

  
printf("Please enter the name of the file: ");
    
    bzero(filename,256);
    fgets(filename,255,stdin);
    
   
      if ( (in=fopen(filename,"rb")) == NULL )
        {
          printf("Could not open %s", filename);
          exit(1);
        }
      else
    	  printf("File exists.");

valaris · 07-08-2009, 04:47 PM

It depends...If you know your process will not change its working directory, and the files will be relative to that location, then ask for a filename. Other then that you should probably get the full path to the file. You can also ask for a filename if all file selections will be relative to some pre known directory.

Cactus_Hugger · 07-08-2009, 05:49 PM

Code:

    bzero(filename,256);
    fgets(filename,255,stdin);

fgets() will terminate the string with a \0 -- there is no need to bzero() the buffer here. Furthermore, you can pass 256, if that's the actual size of filename.

brewbuck · 07-08-2009, 06:59 PM

bzero()? Let me guess, you're using some coding tutorial written by an El1t3 H4kkx0r?

TaiL · 07-13-2009, 03:54 PM

Quote:

Originally Posted by brewbuck

bzero()? Let me guess, you're using some coding tutorial written by an El1t3 H4kkx0r?

yup

TaiL · 07-13-2009, 04:53 PM

ok so i still don't get whats going on here

Code:

int main()
{
	char c;
	unsigned char filename[256];
	FILE *file;

	printf("Please enter the name of the file: ");
	fgets(filename,255,stdin);


	file = fopen(filename, "r");

	if(file == NULL){

		printf("Error: can't open file: %s.\n", filename);
		return 1;
	}
	else{
		printf("File opened successfully. Contents: \n\n ");

		while(1){
			c = fgetc(file);
			if(c!=EOF){
				printf("%c", c);
			}

			else{
				break;
			}
		}

		printf("\n\n Now closing file . . . \n");
		fclose(file);
		return 0;

	}
}

if i pass in "text.txt" into the command line (same folder) shouldn't it be able to open it?

bithub · 07-13-2009, 05:02 PM

No. The problem is that when you type in "text.txt", what actually goes into your buffer is "text.txt\n". A newline character is at the end of your filename string. You need to remove this newline character before you call fopen().

slingerland3g · 07-13-2009, 05:05 PM

Check the value of int file.

07-08-2009, 04:38 PM	#1
TaiL Registered User Join Date: Oct 2008 Posts: 63	Networks Project fopen (input filename) Hi there sorry if this is a repost, I am in a networking course and have a question (with many more to come). First off a little bit about the proj, its an FTP stop and wait program. As of right now I have created the sockets and have been able to connect and send txt. No I am trying to send data. My first step is taken a file name inputted by the user. Question is do i ask for filename or filepath Code: printf("Please enter the name of the file: "); bzero(filename,256); fgets(filename,255,stdin); if ( (in=fopen(filename,"rb")) == NULL ) { printf("Could not open %s", filename); exit(1); } else printf("File exists.");
TaiL is offline

07-08-2009, 04:47 PM	#2
valaris Registered User Join Date: Jun 2008 Location: RING 0 Posts: 460	It depends...If you know your process will not change its working directory, and the files will be relative to that location, then ask for a filename. Other then that you should probably get the full path to the file. You can also ask for a filename if all file selections will be relative to some pre known directory.
valaris is offline

07-08-2009, 05:49 PM	#3
Cactus_Hugger int x = ((int ) NULL); Join Date: Jul 2003 Location: Banks of the River Styx Posts: 890	Code: bzero(filename,256); fgets(filename,255,stdin); fgets() will terminate the string with a \0 -- there is no need to bzero() the buffer here. Furthermore, you can pass 256, if that's the actual size of filename. __________________ long time; /* know C? */ Unprecedented performance: Nothing ever ran this slow before. Any sufficiently advanced bug is indistinguishable from a feature. Real Programmers confuse Halloween and Christmas, because dec 25 == oct 31. The best way to accelerate an IBM is at 9.8 m/s/s. recursion (re - cur' - zhun) n. 1. (see recursion)
Cactus_Hugger is offline

07-08-2009, 06:59 PM	#4
brewbuck Senior software engineer Join Date: Mar 2007 Location: Portland, OR Posts: 5,357	bzero()? Let me guess, you're using some coding tutorial written by an El1t3 H4kkx0r? __________________ "Congratulations on your purchase. To begin using your quantum computer, set the power switch to both off and on simultaneously." -- raftpeople@slashdot
brewbuck is offline

07-13-2009, 05:02 PM	#7
bithub Registered User Join Date: Sep 2004 Location: California Posts: 2,805	No. The problem is that when you type in "text.txt", what actually goes into your buffer is "text.txt\n". A newline character is at the end of your filename string. You need to remove this newline character before you call fopen().
bithub is offline

07-13-2009, 05:05 PM	#8
slingerland3g Registered User Join Date: Jan 2008 Location: Seattle Posts: 457	Check the value of int file.
slingerland3g is offline

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