c - Why do I get smiley characters while reading a txt file? -

i trying continuously read text file don't know doing wrong here. keeps printing me non-printable ascii characters.

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <signal.h> #include <fcntl.h> #include <errno.h> #include <sys/types.h> #include "windows.h"  int main(int argc, char **argv) {     int n, fd;     char buff[256];     if (argc != 2)     {         fprintf(stderr, "usage: %s <filename>\n", argv[0]);         return 1;     }      fd = open(argv[1], o_rdonly);     if (fd < 0)     {         perror("open");         return 1;     }     else if (lseek(fd, 0, seek_end) < 0)     {         perror("lseek");         return 1;     }     else     {         while (1)         {             n = read(fd, buff, sizeof(buff));             if (n < 0)             {                 perror("read");                 break;             }             if (n == 0)             {                 puts(buff);                 sleep(100);                 continue;             }             if (write(stdout_fileno, buff, n) < 0)             {                 perror("write");                 break;             }         }        }     return 0; } 

as argument, pass filename contains information this:

foo-12- 

the output this:

the problem line:

puts(buff); 

when read() returns 0, means you've reached end of file, there's nothing print. printed contents of file in previous iterations of loop, on line with:

write(stdout_fileno, buff, n) 

the puts() printing whatever garbage happens in buff. , since buff isn't null-terminated, may continue printing far past end of array, until finds null byte.

get rid of line.

the reason you're not printing contents of file because @ beginning do:

lseek(fd, 0, seek_end) 

this goes end of file before tries read anything. program display contents added file after start program. because of sleep(100), wait 100 seconds before prints next chunk.