need help with c

Applications Programming
1

hello guys

i am trying to code a program that will read the last line from a file using c language. i got no experience with c, so my code is giving me plenty of errors. could you help me debug ??

code:

 
# include <stdio.h>
 
typedef int function;

void main(void){
int count = 0;
char *numbers;
function x;
 
  while ( count < 200){
    count++;
    x = readlastline(numbers);
  }
}
 
function readlastline(char *f_name){
 
FILE *f_ptr = fopen(f_name, "r");
long first_l = fseek(f_ptr, 0);
int p = -1;
char t = " ";
 
 while (t != "\n"){
  fseek(f_ptr, p, SEEK_END);
  if(ftell(f_ptr) == first_l){
   break;
  }
  t = fgetc(f_ptr);
  p = p - 1;
 }
 t = fgets(f_ptr);
 fclose(f_ptr);
 return t;
}

Much love

2 
#include<stdio.h>

FILE *file_pointer();

main()
{

        char line[80];
        FILE *last=file_pointer();
        fgets (line,80,last) ; // Reading the last line
        printf ( "%s",line ) ; // displaying the last line
}
FILE *file_pointer()
{
        FILE *fp ;
        fp = fopen ("text","r") ;  // Open the file
        fseek(fp,0L,SEEK_END);    // Seek the file pointer to end
        int last = ftell ( fp ) ;
        fseek ( fp,0L,SEEK_SET ) ;
        int first =ftell (fp ) ;
        int i = 0;
        int c ;
        int len = last - first ;
        while ( i++ < len  )        // Doing the operation till file start
        {
                fseek(fp,-i,SEEK_END); // Seeking the file pointer to first from end
                c =fgetc (fp);         // Getting the character for checking new line
                if ( c=='\n')          // If it is new line , Getting the character
                                       // Till next new line character
                {
                        while ( i++ < len )
                        {
                        fseek ( fp , -i , SEEK_END ) ;
                        if ( (c=fgetc( fp)) == '\n' )
                        {
                                return fp ; // Returning the file pointer

                        }

                        }
                }
        }
}
3

thanks pavun

but there is still a problem, your code is giving me error for the following line " int last = ftell(fp)", it says " int not expected ". how could it be when ftell returns a long ?

4

Actually It is working fine in my environment .
I think it could be , because of different type of data types.
ftell return long , But I stored in int . You change the data type of
first , last variable into long date type , It will work.

Thanks

5

minix can be very annoying sometimes ! i have changed both last and first into long. but, it's still giving me the same error. now it says " long not expected "

your code looks right to me

thankx bro

6

Might be a strange idea, but try changing the comments started by // into /* */ comments, eg

// Seek the file pointer to end

to

/* Seek the file pointer to end */

The reason is this: correct ANSI C doesn't support the double-slash comments, since those were originally introduced by C++. So if your compiler is very strict about this (and you being on Minix this might well be) it will fail on those.

7

fseek is used for binary files to change the file position indicator in the stream, to read the last line you can simply read the file untill EOF with fgets.

8

i have changed the comment style , but i am still having the same problem

minix = assassin

please help me guys

9 
 

#include<stdio.h>
#include<string.h>

main()
{
        FILE *fp ;
        char line[80];
        char temp[80];
        fp = fopen ("text","r") ;  // Open the file
        while (fgets (line,80,fp)!= NULL );
        printf ( "%s",line ) ; // displaying the last line
}
10

That's not true? ANSI as adopted ISO/IEC 9899:1999, and // comment style is supported by ISO C99.

I know, people use to think of "ANSI C" as ISO/IEC 9899:1990, but this is strictly speaking wrong since many years :wink:

Cheers,
Lo�c