Sponsored Content
Top Forums Programming Problem with fgets and rewind function .. Post 302165190 by user_prady on Thursday 7th of February 2008 02:27:13 AM
Old 02-07-2008
Problem with fgets and rewind function ..

Hello Friends,

I got stuck with fgets () & rewind() function .. Please need help..

Actually I am doing a like,
The function should read lines from a txt file until the function is called..
If the data from the txt file ends then it goes to the top and then again when the function is called it should display me the top row .. I am doing like below , But it's not doing what I am expecting

Please need help..

Code:
#include <stdio.h>
 
FILE* fileopen();
void read_line(void*);
 
void read_line(void *fh){
              char s[50];
              int i,n;
                            if( fgets(s,49,fh) != NULL) {
                                n = 0;
                                    while(isspace(s[n])){
                                        n++;
                                        if(s[n] == '/' && s[n++] == '/'){
                                                fgets(s,49,fh);
                                }
                             }
                                      printf("%s", s);
                            }
                            else{
                                    rewind(fh);
                            }
}
FILE* fileopen(){
          void *file = fopen("abc1.txt", "r");
            return file;
}
int main(void) {
           void *fh;
            int i;
              fh = fileopen();
               for(i = 0;i < 12; i++){
                 read_line(fh);
                }
              return 0;
}

abc1.txt
Code:
6  7
8 9
12 13

output
Code:
6  7
8 9
12 13
6  7
8 9
12 13
6  7
8 9
12 13

It should give me 12 rows as the function is called 12 times..
but it is returning me 9 rows..

How to solve it I am wondering from last couple of days ..Pls need help badly..

Regards,
prady
 

10 More Discussions You Might Find Interesting

1. Programming

rexec() function problem

Hi folks, I'm trying to make a reconnection algorithm using rexec(), but I noticed that when rexec() fails returning -1, it is impossible to make it run successfully again until you restart the program or the thread. Example, I have a endless loop for connection retries, if I supply a wrong... (7 Replies)
Discussion started by: lcmoreno
7 Replies

2. Programming

fgets()

does anyone knows how to accept a command from a user.. i was wondering to use fgets(), but got no idea how to start it... (4 Replies)
Discussion started by: skanky
4 Replies

3. UNIX for Dummies Questions & Answers

What is the function of rewind()?

What is the function of rewind()? (2 Replies)
Discussion started by: tigerkin
2 Replies

4. UNIX for Dummies Questions & Answers

Need help to understand cpio and no rewind tapes

SCO openserver 5r5 I only have this available to me ... To list the files... cpio -itcvB < /dev/nrct0 To copy a file out cpio -icvdBum filename < /dev/nrct0So cpio is to archive or "zip" files up?? and /dev/nrct0 is the tape drive ??? How can i list all the files inside... (2 Replies)
Discussion started by: khaos83_2000
2 Replies

5. Programming

Question about NULL Character & fgets()

Assume client send the message " Hello ", i get output such as Sent mesg: hello Bytes Sent to Client: 6 bytes_received = recv(clientSockD, data, MAX_DATA, 0); if(bytes_received) { send(clientSockD, data, bytes_received, 0); data = '\0';... (2 Replies)
Discussion started by: f.ben.isaac
2 Replies

6. Programming

[C] fgets problem with SIGINT singlal!!!

Hi all, I have this method to read a string from a STDIN: void readLine(char* inputBuffer){ fgets (inputBuffer, MAX_LINE, stdin); fflush(stdin); /* remove '\n' char from string */ if(strlen(inputBuffer) != 0) inputBuffer = '\0'; } All work fine but if i... (1 Reply)
Discussion started by: hurricane86
1 Replies

7. Programming

fgets problems

I've been having trouble with reading past the end-of-file in C. Can anyone find my stupid mistake? This is the minimal code needed to cause the error for me: FILE *f = fopen(name, "r"); if (!f) return; pari_sp ltop = avma; char line; while(fgets(line, 1100, f) != NULL) printf(".");... (23 Replies)
Discussion started by: CRGreathouse
23 Replies

8. Programming

fgets problems newline

hello, i'm trying to write a C-program that reads a file line by line. (and searches each line for a given string) This file is an special ASCII-database-file, with a lot of entries. I checked the line with most length, and it was about 4000 characters. With google i found several... (4 Replies)
Discussion started by: p1cm1n
4 Replies

9. Programming

How do I copy or rewind *argv[]

I'm working on my own pow function and I need to make a copy of *argv but I think that I am having trouble with the size of *argv and the size of any array that I make. The code below isn't working for me. and I want to accept any number no matter the size with pow -f 2 2. I was working out... (16 Replies)
Discussion started by: Errigour
16 Replies

10. Shell Programming and Scripting

Function problem

hey guys, im trying to learn bourne shell atm and I'm having some issues with functions. so heres my code: #!/bin/bash ##functions memory () { free -m } space () { df -h } ip () { (5 Replies)
Discussion started by: hawkfro12
5 Replies
FGETS(3)						   BSD Library Functions Manual 						  FGETS(3)

NAME
fgets, gets -- get a line from a stream LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <stdio.h> char * fgets(char * restrict str, int size, FILE * restrict stream); char * gets(char *str); DESCRIPTION
The fgets() function reads at most one less than the number of characters specified by size from the given stream and stores them in the string str. Reading stops when a newline character is found, at end-of-file or error. The newline, if any, is retained. If any characters are read and there is no error, a '' character is appended to end the string. The gets() function is equivalent to fgets() with an infinite size and a stream of stdin, except that the newline character (if any) is not stored in the string. It is the caller's responsibility to ensure that the input line, if any, is sufficiently short to fit in the string. RETURN VALUES
Upon successful completion, fgets() and gets() return a pointer to the string. If end-of-file occurs before any characters are read, they return NULL and the buffer contents remain unchanged. If an error occurs, they return NULL and the buffer contents are indeterminate. The fgets() and gets() functions do not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred. ERRORS
[EBADF] The given stream is not a readable stream. The function fgets() may also fail and set errno for any of the errors specified for the routines fflush(3), fstat(2), read(2), or malloc(3). The function gets() may also fail and set errno for any of the errors specified for the routine getchar(3). SEE ALSO
feof(3), ferror(3), fgetln(3), fgetws(3), getline(3) STANDARDS
The functions fgets() and gets() conform to ISO/IEC 9899:1999 (``ISO C99''). SECURITY CONSIDERATIONS
The gets() function cannot be used securely. Because of its lack of bounds checking, and the inability for the calling program to reliably determine the length of the next incoming line, the use of this function enables malicious users to arbitrarily change a running program's functionality through a buffer overflow attack. It is strongly suggested that the fgets() function be used in all cases. BSD
May 5, 2012 BSD
All times are GMT -4. The time now is 01:26 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy