File_w_r_with_structure1.c

// author: jaydattpatel
#include <stdio.h>
#include <stdlib.h>

struct emp
{
    int serialnum;
    char name[10];
    int age;
};

int main()
{
    int i,n,position;
    struct emp e;
    FILE *fp;
    
    fp = fopen("one.txt", "a");    // "a","ab","a+","ab+","a+b" command use to edit or add data in file and move pointer at last character of file
     if(fp == NULL)
        {printf("fail to open file!");   exit(1);      }
    position = ftell(fp);              // ftell() store the position of pointer to reuse when print data
    
    printf("How many data you want:");
    scanf("%d",&n);
    for(i=0;i<n;i++)
        {
            printf("Enter Sr.num,Name and Age:");
            scanf("%d %s %d",&e.serialnum, e.name, &e.age);
            fprintf(fp,"\n%d %s %d",e.serialnum, e.name, e.age);
        };
    fclose(fp);
     
    fp = fopen("one.txt", "r"); // "r","r+","rb","rb+","r+b" use to open file to read
      if(fp == NULL)
        { printf("fail to open file!");    exit(1);    }
    fseek(fp,position,SEEK_SET);   
      /*
      fseek(FILE *pointer, long int offset, int position); fseek( fp, 7, (SEEK_SET:0,SEEK_CUR:1,SEEK_END:2 ); 
      */  
    for(i=0;i<n;i++)
      {  
        fscanf(fp,"\n%d %s %d",&e.serialnum, e.name,&e.age);
        printf("\n%d %s %d",e.serialnum, e.name,e.age);
      };
    fclose(fp);
}