Thread: doesn't stop before EOF

Enter a filename, enter a number, and the program is supposed to get to that "line" and print it then exit. My plan to accomplish this was count newlines (i < lines) or until EOF and then print a line. However I can't get the program to stop before EOF, it doesn't seem to be paying attention to the i < line part. I've tried swtching || for && in the while loop assuming somehow that was forcing it to wait for the EOF, no help (since it of course should be an && by my logic). I've tried moving the i < lines into the while as an if break and still exact same results.

Code:

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

int main(void)
{
	int i = 0, line, check;
	FILE *fp;
	char words[MAX+1], fname[MAX+1];
	
	puts("Enter filename");
	fgets(fname, 100, stdin);
	
	if((fp = fopen(fname, "r")) == NULL)
		{
		fprintf(stdin, "Can't open %s file.\n", fname);
		exit(1);
		}
	
	puts("Enter the line you wish to see");
	scanf("%d", &line);
	while(i < line && (check = fgetc(fp)) != EOF)
		if(check == '\n')
			i++;
	
	fgets(words, 100, fp);
	puts("Line contents:");
	puts(words);
	
	if(fclose(fp) != 0)
		fprintf(stderr,"Error closing file\n");
	
	return 0;
}

the file I input has the following text

Code:

one two three
test test test
four five six
seven eight nine
ten eleven twelve

[Session started at 2007-08-03 12:53:56 -0400.]
Enter filename
testrun.txt
Enter the line you wish to see
2
Line contents:
\277`\220`\375

Prime has exited with status 0.

and it always prints the same garbage so obviously nothing new is getting read into words, no matter the number I input.

I've also tried changing the if(check == '\n') to
if(check == '\0')
if(check == '\r')
if(check == ' ')
if(check == 32)
if(check == 't')

and still no change

The string "word" contains nothing throughout the program, so don't expect a legible result, especially something like containing the current line you're on.

Originally Posted by citizen

The string "word" contains nothing throughout the program, so don't expect a legible result, especially something like containing the current line you're on.

fgets(words, 100, fp) is supposed to fill it, but since it only reaches that after EOF it's not going to put anything.

I have even changed the code to

Code:

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

int main(void)
{
	int i = 0, line, check;
	FILE *fp;
	char words[MAX+1], fname[MAX+1];
	
	puts("Enter filename");
	fgets(fname, 100, stdin);
	
	if((fp = fopen(fname, "r")) == NULL)
		{
		fprintf(stdin, "Can't open &#37;s file.\n", fname);
		exit(1);
		}
	
	puts("Enter the line you wish to see");
	scanf("%d", &line);
	while(i < line && (check = fgetc(fp)) != EOF)
		if(check == ' ')
			i++;
	
	if (check == EOF)
		printf("\nEnd of file reached before given line\n");
	else
		{
		fgets(words, 100, fp);
		puts("Line contents:");
		puts(words);
		}
	
	if(fclose(fp) != 0)
		fprintf(stderr,"Error closing file\n");
	
	return 0;
}

And it reports the "end of file reached" so it is going all the way to EOF and not terminating when i = line or i > line or i isn't getting incremented.

Originally Posted by zmaker5

Code:

        fprintf(stdin, "Can't open %s file.\n", fname);

slkjgfdnsw;rjkltng

yeah I change it to stdout and it works just the same (even if I test with fake file names with stdin and stdout.)

I originally was going to use a for loop and then thought a while loop would be the best way to check for EOF and read characters at the same time. I'll try reconverting to a for loop and see what happens.

ok changed to

Code:

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

int main(void)
{
	int i = 0, line, check;
	FILE *fp;
	char words[MAX+1], fname[MAX+1];
	
	puts("Enter filename");
	fgets(fname, 100, stdin);
	
	if((fp = fopen(fname, "r")) == NULL)
		{
		fprintf(stdout, "Can't open &#37;s file.\n", fname);
		exit(1);
		}
	
	puts("Enter the line you wish to see");
	scanf("%d", &line);
	
	for(i=0; i < line; i++)
		{
		check = fgetc(fp);
		if (check != EOF)
			if (check == 't')
				i++;			
		else
			break;
		}
		
//	while(i < line && (check = fgetc(fp)) != EOF)
//		if(check == ' ')
//			i++;
	
	if (check == EOF)
		printf("\nEnd of file reached before given line\n");
	else
		{
		fgets(words, 100, fp);
		puts("Line contents:");
		puts(words);
		}
	
	if(fclose(fp) != 0)
		fprintf(stderr,"Error closing file\n");
	
	return 0;
}

and still getting

Code:

[Session started at 2007-08-03 14:54:15 -0400.]
Enter filename
testrun.txt
Enter the line you wish to see
1

End of file reached before given line

Prime has exited with status 0.

though I just double checked the file, and found that when I set it to "w" for fopen it still had the other file by the same name (obviously an empty file) and removed it. Now I can't get the program to see the file, where am I supposed to put it (I'm doing this in Xcode as a project, might have to compile it on Terminal since I know where that looks)

alright I've got the program relatively working in terminal, part of the problem was fgets was grabbing the \n at the end of entry (dunno why I keep forgetting about that)

thanks for your help guys

You second try doesn't make any sense. I think it is completely wrong and it is going nowhere. You first logic was correct.

I think you should not call fgetc() in a for loop , it should be called in a while loop till EOF.

ok it's working now
though could someone explain to me why changing it from i = 0 to i = 1 fixed it? thanks

Code:

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

int main(void)
{
	int i = 1, line, check;
	FILE *fp;
	char words[MAX+1], fname[MAX+1];
	
	puts("Enter filename");
	gets(fname);
//	fgets(fname, 100, stdin);
	
	if((fp = fopen(fname, "r")) == NULL)
		{
		fprintf(stdout, "Can't open &#37;s file.\n", fname);
		exit(1);
		}
	
	puts("Enter the line you wish to see");
	scanf("%d", &line);
	while(i < line && (check = fgetc(fp)) != EOF)
		if(check == '\n')
			i++;
	
	if (check == EOF)
		printf("\nEnd of file reached before given line\n");
	else
		{
		fgets(words, 100, fp);
		puts("Line contents:");
		puts(words);
		}
	
	if(fclose(fp) != 0)
		fprintf(stderr,"Error closing file\n");
	
	return 0;
}