fseek in C

It is used to move the reading control to different positions using fseek function.

C Syntax

 fseek( file pointer, displacement, pointer position);

file pointer : It is the pointer which points to the file.
displacement : It is positive or negative. This is the number of bytes which are skipped backward (if negative) or forward( if positive) from the current position. This is attached with L because this is a long integer.
pointer position : This sets the pointer position in the file.

fseek( p,10L,0)

0 means pointer position is on beginning of the file, from this statement pointer position is skipped 10 bytes from the beginning of the file.

fseek( p,5L,1)

1 means current position of the pointer position. From this statement pointer position is skipped 5 bytes forward from the current position.

fseek(p,-5L,1)

From this statement pointer position is skipped 5 bytes backward from the current position.

Sample Code

#include<stdio.h>
#include<conio.h>
  void main() {
    FILE * fp;
    char ch;
    int n;
    fp = fopen("one.txt", "r");
    if (fp == NULL) {
      printf("file cannot be opened");

    } else {
      printf("Enter value of n to read last ‘n’ characters");
      scanf("%d", & n);
      fseek(fp, -n, 2);
      while ((ch = fgetc(fp)) != EOF) {
        printf("%c\t", ch);
      }
    }
    fclose(fp);
  }