#include <stdio.h>
#include <conio.h>
#include "valid.c"struct student_detail
{
   char name[10];
   int age;
};

 void getWriteFileName(char *str);
 void getReadFileName(char *str);
 void findGSAge();
 void enterData();
 void getName(char *);

 FILE *fp;
 char filename[14];
 int flag=1;
 struct student_detail s_young, s_elder, s_cur;

 void main()
 {
    char option;
    clrscr();
    printf("\nDo you want to create the data file type 'y' for yes and 'n' for no.");
    scanf("%c", &option);
    fflush(NULL);
    if( option == 'y' || option == 'Y')
    getWriteFileName(filename);
    elseif( option == 'n' || option == 'N')
      {   getReadFileName(filename);
      findGSAge();
      }
    getch();
 }

 void enterData()
 {
      s_young.age = 99;
      s_elder.age = 1;
    printf("\nEnter data .....");
    while(flag)
    {
    printf("\nEnter student name : ");
    //scanf("%[^\n]", s_cur.name);
    getName(s_cur.name);
    fflush(NULL);

    //printf("\nEnter student age : ");//scanf("%d", &s_cur.age);
    getPosInteger("Enter student age : ", &s_cur.age);
    fflush(NULL);
    fprintf(fp,"%-10s %d", s_cur.name, s_cur.age);

    if( flag > 0 )
       fprintf(fp,"\n");

    flag++;
    if(s_cur.age != 99)
    {
       printf("\nEnter 1 to continue and 0 to exit.");
       scanf("%d", &flag);
       fflush(NULL);
    }
    else  flag = 0;

      if(s_young.age > s_cur.age)
      {   s_young.age = s_cur.age;
          strcpy(s_young.name, s_cur.name);
      }
      if(s_elder.age < s_cur.age)
      {   s_elder.age = s_cur.age;
          strcpy(s_elder.name, s_cur.name);
      }
    }
    fclose(fp);
      printf("\nYoungest student is : %-10s %d", s_young.name, s_young.age);
      printf("\nOldest student is : %-10s %d", s_elder.name, s_elder.age);
 }

    void getName(char *str)
    {
    int count=0;
    char *getstr;
    char readch='\0';
    int errorflag = 0;

       fflush(NULL);
       getstr = str;

       while(1)
       {
        scanf("%c", &readch);
        if( readch == '\n')
           break;
        if( isalpha(readch) == 0)
        {   printf("\nInvalid entry. Enter characters only.\nEnter name again :");
            errorflag = 1;
            break;
        }
        else
            *getstr = readch;

        count++;
        getstr++;
        if( count >= 10 )
          break;
       }

       if(errorflag)
          getName(s_cur.name);

       //*getstr='\0';
    }

   void getWriteFileName(char *str)
   {
     printf("Enter Output File name maxium 14 character : ");
     scanf("%s", str);

     if( ( fp = fopen(str, "wt") ) == NULL  )
     {  fclose(fp);
    printf("\nInvalid file name entered.");
     }
     else
    enterData();
  }

   void getReadFileName(char *str)
   {
     printf("Enter Input File name maxium 14 character : ");
     scanf("%s", str);

     if( ( fp = fopen(str, "r+t") ) == NULL  )
     {  fclose(fp);
    printf("\nInvalid file name entered.");
     }
   }

   void findGSAge()
   {
      s_young.age = 99;
      s_elder.age = 1;

      while( feof(fp) == 0 )
      {
      fscanf(fp, "%10s %4d", s_cur.name, &s_cur.age);
      if(s_young.age > s_cur.age)
      {   s_young.age = s_cur.age;
          strcpy(s_young.name, s_cur.name);
      }
      if(s_elder.age < s_cur.age)
      {   s_elder.age = s_cur.age;
          strcpy(s_elder.name, s_cur.name);
      }
      fflush(NULL);
      }

      fclose(fp);
      printf("\nYoungest student is : %-10s %d", s_young.name, s_young.age);
      printf("\nOldest student is : %-10s %d", s_elder.name, s_elder.age);
   }

    /*******************************  Input/Ouput ********************************/



        Do you want to create the data file type 'y'for yes and 'n'for no.y
        Enter Output File name maxium 14 character : output.txt

        Enter data .....
        Enter student name : nilay

        Enter student age : 44

        Enter 1 to continue and 0 to exit.1

        Enter student name : chintan

        Enter student age : 99

        Youngest student is : nilay      44
        Oldest student is : chintan    99

    /*******************************************************************************/