//readtest.c --- @copyLeft by tsaiwn@csie.nctu.edu.tw
// This program reads data from studat.txt ..
// .. into an array which is actually in Heap memory area.
// This program also shows you how to use struct to group data.
// Since we do NOT know how large the memory required, 
//  we have to read ALL data before allocating the memory.
// We use "malloc" to allocate an array for student data.
#define MAX_STU 99999
#define fileName "studat.txt"
#include <stdio.h>
#include <string.h>
typedef struct {
   long id;  int h, m, q, f;
   double total;  // 學期總成績= (h*0.2 + m*0.3 + q*0.1+f*0.4); 
   long rank, recno;  // rank, original record number
   char name[9];  // student's name
} Student_t;   // 這種命名方式是不錯的習慣
///
long aid[MAX_STU]; // Students ID
int as1[MAX_STU], as2[MAX_STU], as3[MAX_STU], as4[MAX_STU];
long arank[MAX_STU], arec[MAX_STU];
double atotal[MAX_STU];
char aname[MAX_STU][9]; // Students name
long nOfStu;
long countF(char*fName);  // count records in fName
Student_t * y; // a pointer to a Student_t
void readOne( ), readTwo(Student_t x[ ], char*fileNM);
void printRec(Student_t);  // print one Student
int main( ) {
    long k;
    FILE* fp = fopen(fileName, "rt");  // read, text
    if(fp==0) {printf(" %s NOT found!",fileName); getchar( );return 1;}
    fclose(fp); // close it since I just want to make sure it's OK
    readOne( );  // read into all data array
    printf("First: %8d %8s %3d %3d %3d %3d %5.2f\n", aid[0], aname[0], 
             as1[0], as2[0], as3[0], as4[0], atotal[0]);
    k = nOfStu -1; // last student
    printf(" Last: %8d %8s %3d %3d %3d %3d %5.2f\n", aid[k], aname[k], 
             as1[k], as2[k], as3[k], as4[k], atotal[k]);
    nOfStu = countF(fileName);
    /// then, 
     /// allocate memory for y[ ] which will store all students
    y = (Student_t *) malloc(sizeof(Student_t) * nOfStu);
    printf("=== === Now test readTwo( )\n");
    readTwo(y, fileName);  // read into y[ ], which is in Heap area
    printf(" 1st_record: ");  printRec(y[0]);
    printf(" 2nd_record: ");  printRec(y[1]);
    printf(" 3rd_record: ");  printRec(y[2]);
    printf(" ... then, the last 3 records:\n");
    for(k= nOfStu-3; k < nOfStu; k++) {
        printf(" %6ld_rec: ", k+1);   // 從 1 算起所以要 + 1
        printRec(y[k]);  // y[k]; 注意這只是 "第幾筆" 叫法不同
    }// for k
    fprintf(stderr, "\nHit ENTER key...");
    getchar( ); return 0;
} // main(
void readOne( ) {   // 讀到各個 Array, 不使用 struct
    FILE* fp = stdin; // file pointer
    long id; char name[9]; int s1, s2, s3, s4, kk;
    long rank, recno=0;
    static char buf[999];
    fp = fopen(fileName, "rt");  // read, text
    if(fp==0) return;  // Error when open
    fgets(buf, sizeof(buf), fp);  // stdin
    printf("Line1: %s", buf);
    kk=0;
    while( ! feof(fp) ) {
       sscanf(buf,"%ld %s %d %d %d %d", 
                  &id, name, &s1, &s2, &s3,&s4);
      aid[kk]=id; strcpy(aname[kk], name);
      as1[kk]=s1; as2[kk]=s2; as3[kk]=s3; as4[kk]=s4;
      ++kk; 
      buf[0]=0; fgets(buf, sizeof(buf), fp); 
    }
    if(buf[0] !=0 ) {
       fprintf(stderr, " Warning: last line has no new line.\n");
       // 還有ㄟ,  須抓出資料塞入各 array [kk] 
       ++kk;  // count it ! 當然這也要算喔 !
    }
    nOfStu = kk;  // global variable nOfStu
    fprintf(stderr, "Total %d records.\n", kk);
}// readOne(
long countF(char* fnm) {  // how many records in file fnm
    long kk = 0;  static char buf[999];
    FILE* fp = fopen(fnm, "rt");  // read, text
    if(fp==0) return 0; // open error, nothing read
    buf[0]=0;  // ensure the buffer is empty before read
    fgets(buf, sizeof buf, fp); 
    while( ! feof(fp) ) {
       ++kk;  buf[0]=0; 
       fgets(buf, sizeof(buf), fp); 
    } fclose(fp); // close it
    if(buf[0] !=0 ) {  // got something in buf[ ]
       fprintf(stderr, " Warning: last line has no new line.\n");
       ++kk;  // count this record
    }  
    return kk;
}//countF
void readTwo(Student_t * x, char*fnm) {  //有使用 struct; 讀檔案 fnm
    static char buf[999];  
    long i = 0;
    Student_t tmp;   // temporary student of struct Student_t
    FILE* fp = fopen(fnm, "rt");  // read, text
    if(fp == 0) return; // Open Fail !
    for(;;) {
        buf[0]=0; fgets(buf, sizeof buf, fp); //read one record
        if(feof(fp))break;  // EOF encounted
        sscanf(buf,"%ld %s %d %d %d %d", 
             &tmp.id, tmp.name, &tmp.h, &tmp.m, &tmp.q,&tmp.f);
        tmp.total = tmp.h*0.2 + tmp.m*0.3 + tmp.q*0.1+ tmp.f*0.4;
        x[i++] = tmp;   // 把該 struct tmp 放入 第 i 學生 x[i]
    }// for
    if(buf[0]) {   // one more record in buf[ ] ; 最後一列沒 NewLine
        sscanf(buf,"%ld %s %d %d %d %d", 
             &tmp.id, tmp.name, &tmp.h, &tmp.m, &tmp.q,&tmp.f);
        tmp.total = tmp.h*0.2 + tmp.m*0.3 + tmp.q*0.1+ tmp.f*0.4;
        x[i++] = tmp;   // 這最後一個也要喔 !
    }
} // readTwo(
void printRec(Student_t s) {  // print the Student s
    printf("%8ld %8s %3d %3d %3d %3d %5.2f   %6ld",
      s.id, s.name, s.h, s.m, s.q, s.f, s.total, s.rank);
    printf("\n");
    // 學期總成績= (h*0.2 + m*0.3 + q*0.1+f*0.4); 
} // printRec(
/******
Line1: 9938596     章LUf  76  74  79  98
Total 81482 records.
First:  9938596    章LUf  76  74  79  98  0.00
 Last:  9998482    林OCh   5  94  90  77  0.00
=== === Now test readTwo( )
 1st_record:  9938596    章LUf  76  74  79  98 84.50        1
 2nd_record:  9934067    趙NLv  72  64  61  94 77.30        1
 3rd_record:  9947865    魏NEu  86  98  58  90 88.40        1
 ... then, the last 3 records:
  81480_rec:  9998480    馬BNt  75  79  71  67 72.60        1
  81481_rec:  9998481    馬GVn  74  57  61  86 72.40        1
  81482_rec:  9998482    林OCh   5  94  90  77 69.00        1

Hit ENTER key...
*****************/