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:
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;
}
Use this code to get the last line of the file .
I have written the function for finding the last line file pointer
Code:
#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
}
}
}
}
}
Last edited by pavun_cool; 02-26-2010 at 01:19 AM..
Reason: Adding some statements
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 ?
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.
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 "
Might be a strange idea, but try changing the comments started by // into /* */ comments, eg
Code:
// Seek the file pointer to end
to
Code:
/* 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.
i am trying to code a program that will read the last line from a file using c language.
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.
