file

[saurav sarkar]

could anyone point what went wrong with the code.
I am just trying to display the contents of the file poem.txt on the screen.
# include<stdio.h>
void main()
{
FILE*fp;
char s[80];
fp=fopen("poem.txt","r");
if(fp==NULL)
{
puts("cannot open the file");
exit();
}
while(fgets(s,79,fp)!=NULL)
printf("%s",s);
fclose(fp);
getch();
}
compiler is not giving any error,but still i am not getting the output.

[Inept Pig]

Works fine on mine, although I had to include the stdlib and conio librarys to make it work.

As a future note, void main() is largely regarded as bad, main should return a value.

What happened when you ran the code?

[Prelude]

>void main()
No, int main ( void ).

>exit();
exit must have an argument of 0, EXIT_FAILURE, or EXIT_SUCCESS to be portable. No argument is an error. You also haven't included stdlib.h.

>getch();
Not portable and you didn't include conio.h.

Here are my corrections, I switched getchar with getch for portability reasons. If you want to change back do not forget to include conio.h.

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
  FILE*fp;
  char s[80];
  fp=fopen("poem.txt","r");
  if(fp==NULL)
  {
    puts("cannot open the file");
    exit(0);
  }
  while(fgets(s,79,fp)!=NULL)
    printf("%s",s);
  fclose(fp);
  getchar();
  return 0;
}

-Prelude

[Hammer]

>>char s[80];
>>while(fgets(s,79,fp)!=NULL)
Aren't you wasting a byte of the buffer?

[ronin]

As those files get larger, you might also consider something like.

int rows;

....

rows = 0;
while(fgets(s,79,fp)!=NULL)
{
    if(rows == 22)
    {
         printf("\npress any key to continue.\n");
         getchar();
         rows = 0;
    }
     else
         printf("%s",s);
  
    rows++;
}
fclose(fp);

[Monster]

Remove the else

[ronin]

yikes, force of habit.

[moonwalker]

is this how they go around between rows of a text file ?
do i have to loop 100 times if i want to go to the 100th line ?
or is there a better way ?

[Hammer]

Originally posted by moonwalker
is this how they go around between rows of a text file ?
do i have to loop 100 times if i want to go to the 100th line ?
or is there a better way ?

If you know how long each "line" is then you can seek to the correct location, otherwise you're stuck with looping through the input counting the lines.

[Bill 101]

Hi,

Try this code. It uses fread instead of fgets(). It gets the actual file size for you, so you can read in any text file in any size.

Hope it helps! -


#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

int main(void)
{
off_t fsize = 0;

FILE*fp;
fp=fopen("poem.txt","r");
if(fp==NULL)
{
puts("cannot open the file");
exit(0);
}

struct stat attributes; struct stat *attributes_ptr;
attributes_ptr = &attributes;
stat("poem.txt",attributes_ptr);

fsize = attributes_ptr -> st_size;
char s[fsize - 1];


fread(s,fsize,1,fp);
printf("%s",s);
return 0;
}

[quzah]

Originally posted by Bill 101
Hi,

Try this code. It uses fread instead of fgets(). It gets the actual file size for you, so you can read in any text file in any size.

fsize = attributes_ptr -> st_size;
char s[fsize - 1];


fread(s,fsize,1,fp);
printf("%s",s);
return 0;
}

This is not valid C code. In C, you cannot declare variables in the middle of the code block. You must do so at the beginning. Furthermore, this may or may not work on all compilers--actually, it will not work on all compilers--unless they conform to C99 specifications, due to the fact that you're using a variable sized array.

Quzah.