//genscore.c
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
char nameLast[ ][3]={"趙", "錢", "孫", "李", "陳", "林",
        "吳", "魏", "王", "蔡", "章", "張", "簡" };
const int N_LAST = (sizeof(nameLast) / sizeof(nameLast[0]) );
#define NSTU_MIN  3388
#define NSTU_MAX  8888
#define ID_BASE 9917001
#define FILE_NAME "studat.txt"
int myRand( ) {
   return rand( ) % 100;
}
void genName(char*p) {
  char mm,m2,m3;  char tmps[5]={0};
  *p = 0; // 清除字串
  strcat(p, nameLast[rand( )% N_LAST]);
  mm = 'A' + rand( )%26;
  m2 = 'A' + rand( )%26;
  m3 = 'a' + rand( )%26;
  sprintf(tmps, "%c%c%c", mm, m2, m3);
  strcat(p, tmps);
}    
extern int nStudent;
long genID( ) {
   static char idFlag[NSTU_MAX];
   int k = rand( ) % nStudent;
   int nTry = 0;
   while(idFlag[k] !=0) {
       k = rand( ) % nStudent;
       if(++nTry > 10) break;
   }
   if(idFlag[k]!=0) { // 已經用過
      k=0;
      while(idFlag[k] !=0) ++k;
   }
   idFlag[k] = 1;
   return ID_BASE + k;
}
///
 int nStudent;
 long sid;
 char name[9];
 int hwk, mid, quiz, fin;
void getNextStuData( ) {
   sid = genID( ); genName(name);
   hwk = myRand( );
   mid = myRand( );
   quiz = myRand( );
   fin = myRand( );
}
int main( ) {
    FILE* fp;
    int i;
    srand( time(0) );  // randomize
    int n = NSTU_MIN + rand( ) % 200;
    nStudent = n;
    fp = fopen(FILE_NAME, "wt");
    if(fp == 0) { fprintf(stderr, "Sorry error...\n"); return 1; }
    for(i = 1; i<= n; ++i) {
       getNextStuData( );
       fprintf(fp, "%7d %9s %3d %3d %3d %3d\n",
         sid, name, hwk, mid, quiz, fin);
    }
    fclose(fp);
    fprintf(stderr, "File %s generated successfully.\n", FILE_NAME);
    fprintf(stderr, "Total %d student records.\n", n);
    return 0;
}