Question

C programming.

Use open(), lseek(), and read() to get the integer from the second line of the text file.

The text file is in lines of 32 bytes, the integer is 6 bytes, as shown:

000000 xxxxxxxxxxxxxxxxxxxxxxxx

111111 xxxxxxxxxxxxxxxxxxxxxxx

222222 xxxxxxxxxxxxxxxxxxxxxxx

Answer 1

Program

#include<stdio.h>
#include<fcntl.h>

int main()
{
// open the the in read-only mode
int f = open("file.txt", O_RDONLY);
  
if (f ==-1)
{
// print program detail "Success or failure"
perror("Program");
}
  
long offset = 32;
  
// forward current position 32 bytes
lseek (f, offset, SEEK_CUR);
  
char buf[6];
  
// read 6 bytes of input store in buf
read(f, buf, 6);
  
// convert from string to int
int i = atoi(buf);
  
// display the integer
printf("%d", i);
  
close(f);
  
return 0;
}

Output:

111111