Project: thiết kế hệ quản lý sinh viên

main.c        chi phan tich tham so dong lenh va goi vong lap menu
   |
ui.c          hien thi menu, doc lua chon, doc du lieu tu nguoi dung
   |          KHONG biet du lieu duoc luu the nao
quanly.c      mang dong, them, xoa, sua, tim, sap xep, thong ke
   |          KHONG biet gi ve tep, KHONG in ra man hinh
luutru.c      doc ghi nhi phan
csv.c         doc ghi CSV
   |          KHONG biet gi ve mang dong, chi lam viec voi mang thuong
sinhvien.c    mot sinh vien: kiem tra hop le, so sanh, dinh dang
              KHONG phu thuoc gi ca

#ifndef LOI_H
#define LOI_H

typedef enum {
    QL_OK = 0,

    /* Du lieu vao */
    QL_MSSV_SAI,
    QL_TEN_RONG,
    QL_DIEM_NGOAI_KHOANG,
    QL_NAM_SINH_SAI,
    QL_TRUNG_MSSV,
    QL_KHONG_TIM_THAY,

    /* Bo nho */
    QL_HET_BO_NHO,

    /* Tep */
    QL_LOI_MO_TEP,
    QL_LOI_GHI,
    QL_LOI_DOC,
    QL_TEP_HONG,
    QL_SAI_PHIEN_BAN,
} MaLoi;

const char *ql_mo_ta_loi(MaLoi m);

#endif

#ifndef SINHVIEN_H
#define SINHVIEN_H

#include <stdint.h>

#include "loi.h"

#define SV_MSSV_CO    16
#define SV_TEN_CO     64
#define SV_LOP_CO     16
#define SV_SO_MON      5

typedef struct {
    char     mssv[SV_MSSV_CO];
    char     ho_ten[SV_TEN_CO];
    char     lop[SV_LOP_CO];
    uint16_t nam_sinh;
    char     gioi_tinh;                    /* 'M' hoac 'F' */
    uint16_t diem_x100[SV_SO_MON];         /* 8.25 luu la 825 */
    uint8_t  con_hoat_dong;                /* 0 la da xoa mem */
} SinhVien;

/* Tinh tu diem_x100, khong luu vao tep */
uint16_t    sv_diem_tb_x100(const SinhVien *sv);
const char *sv_xep_loai(const SinhVien *sv);

/* Kiem tra hop le, tra ve QL_OK hoac ma loi cu the */
MaLoi sv_kiem_mssv(const char *s);
MaLoi sv_kiem_ten(const char *s);
MaLoi sv_kiem_diem(uint16_t diem_x100);
MaLoi sv_kiem_nam_sinh(uint16_t nam);
MaLoi sv_kiem_tat_ca(const SinhVien *sv);

#endif

#include "sinhvien.h"

uint16_t sv_diem_tb_x100(const SinhVien *sv) {
    uint32_t tong = 0;

    for (int i = 0; i < SV_SO_MON; ++i) tong += sv->diem_x100[i];

    /* Lam tron toi so gan nhat thay vi cat bo */
    return (uint16_t)((tong + SV_SO_MON / 2) / SV_SO_MON);
}

const char *sv_xep_loai(const SinhVien *sv) {
    uint16_t tb = sv_diem_tb_x100(sv);

    if (tb >= 900) return "Xuat sac";
    if (tb >= 800) return "Gioi";
    if (tb >= 650) return "Kha";
    if (tb >= 500) return "Trung binh";

    return "Yeu";
}

#include <ctype.h>
#include <string.h>

MaLoi sv_kiem_mssv(const char *s) {
    size_t n = strlen(s);

    if (n != 8) return QL_MSSV_SAI;                 /* dung 8 chu so */

    for (size_t i = 0; i < n; ++i)
        if (!isdigit((unsigned char)s[i])) return QL_MSSV_SAI;

    return QL_OK;
}

MaLoi sv_kiem_ten(const char *s) {
    size_t n = strlen(s);

    if (n == 0 || n >= SV_TEN_CO) return QL_TEN_RONG;

    /* Khong duoc toan khoang trang */
    for (size_t i = 0; i < n; ++i)
        if (!isspace((unsigned char)s[i])) return QL_OK;

    return QL_TEN_RONG;
}

MaLoi sv_kiem_diem(uint16_t d) {
    return d <= 1000 ? QL_OK : QL_DIEM_NGOAI_KHOANG;   /* 0.00 den 10.00 */
}

MaLoi sv_kiem_nam_sinh(uint16_t nam) {
    return (nam >= 1950 && nam <= 2020) ? QL_OK : QL_NAM_SINH_SAI;
}

MaLoi sv_kiem_tat_ca(const SinhVien *sv) {
    MaLoi m;

    if ((m = sv_kiem_mssv(sv->mssv))         != QL_OK) return m;
    if ((m = sv_kiem_ten(sv->ho_ten))        != QL_OK) return m;
    if ((m = sv_kiem_nam_sinh(sv->nam_sinh)) != QL_OK) return m;

    for (int i = 0; i < SV_SO_MON; ++i)
        if ((m = sv_kiem_diem(sv->diem_x100[i])) != QL_OK) return m;

    if (sv->gioi_tinh != 'M' && sv->gioi_tinh != 'F') return QL_MSSV_SAI;

    return QL_OK;
}

#ifndef QUANLY_H
#define QUANLY_H

#include <stddef.h>

#include "sinhvien.h"

typedef struct {
    SinhVien *ds;
    size_t    n;              /* so phan tu dang dung */
    size_t    suc_chua;       /* so phan tu da cap phat */
    int       da_thay_doi;    /* co bao can luu */
} QuanLy;

void  ql_khoi_tao(QuanLy *q);
void  ql_giai_phong(QuanLy *q);

MaLoi ql_them(QuanLy *q, const SinhVien *sv);
MaLoi ql_xoa(QuanLy *q, const char *mssv);
MaLoi ql_sua(QuanLy *q, const char *mssv, const SinhVien *moi);

long  ql_tim_mssv(const QuanLy *q, const char *mssv);   /* -1 neu khong thay */

#endif

#include <stdlib.h>
#include <string.h>

#include "quanly.h"

#define SUC_CHUA_DAU 16

void ql_khoi_tao(QuanLy *q) {
    q->ds           = NULL;
    q->n            = 0;
    q->suc_chua     = 0;
    q->da_thay_doi  = 0;
}

void ql_giai_phong(QuanLy *q) {
    free(q->ds);
    ql_khoi_tao(q);            /* dat lai NULL, tranh con tro treo */
}

static MaLoi bao_dam_cho(QuanLy *q, size_t can) {
    if (can <= q->suc_chua) return QL_OK;

    size_t moi = q->suc_chua ? q->suc_chua * 2 : SUC_CHUA_DAU;

    while (moi < can) moi *= 2;

    if (moi > SIZE_MAX / sizeof *q->ds) return QL_HET_BO_NHO;   /* chong tran */

    SinhVien *tam = realloc(q->ds, moi * sizeof *q->ds);

    if (!tam) return QL_HET_BO_NHO;      /* q->ds VAN CON NGUYEN */

    q->ds       = tam;
    q->suc_chua = moi;

    return QL_OK;
}

MaLoi ql_them(QuanLy *q, const SinhVien *sv) {
    MaLoi m = sv_kiem_tat_ca(sv);

    if (m != QL_OK) return m;

    if (ql_tim_mssv(q, sv->mssv) >= 0) return QL_TRUNG_MSSV;

    if ((m = bao_dam_cho(q, q->n + 1)) != QL_OK) return m;

    q->ds[q->n] = *sv;                   /* sao chep ca struct, khong con tro */
    q->ds[q->n].con_hoat_dong = 1;
    ++q->n;
    q->da_thay_doi = 1;

    return QL_OK;
}

long ql_tim_mssv(const QuanLy *q, const char *mssv) {
    for (size_t i = 0; i < q->n; ++i)
        if (q->ds[i].con_hoat_dong && strcmp(q->ds[i].mssv, mssv) == 0)
            return (long)i;

    return -1;
}

MaLoi ql_xoa(QuanLy *q, const char *mssv) {
    long i = ql_tim_mssv(q, mssv);

    if (i < 0) return QL_KHONG_TIM_THAY;

    /* Xoa that: don cac phan tu sau len mot o */
    memmove(&q->ds[i], &q->ds[i + 1], (q->n - (size_t)i - 1) * sizeof *q->ds);

    --q->n;
    q->da_thay_doi = 1;

    return QL_OK;
}

#ifndef LUUTRU_H
#define LUUTRU_H

#include "sinhvien.h"

/* Ca hai tang deu lam viec voi MANG THUONG, khong biet gi ve QuanLy.
   Nho vay chung kiem thu duoc rieng, va dung lai duoc o cho khac. */

MaLoi lt_ghi_nhi_phan(const char *ten, const SinhVien *ds, size_t n);
MaLoi lt_doc_nhi_phan(const char *ten, SinhVien **ra_ds, size_t *ra_n);

MaLoi csv_ghi(const char *ten, const SinhVien *ds, size_t n);
MaLoi csv_doc(const char *ten, SinhVien **ra_ds, size_t *ra_n,
              size_t *ra_so_dong_hong);

#endif

Phan dau, 16 byte:
    0   magic[4]        "SVDB"
    4   phien_ban       u32, hien tai la 1
    8   so_ban_ghi      u32
   12   ma_kiem         u32, FNV-1a tren toan bo vung du lieu

Moi ban ghi, 112 byte:
    0   mssv[16]
   16   ho_ten[64]
   80   lop[16]
   96   nam_sinh        u16
   98   gioi_tinh       1 byte
   99   con_hoat_dong   1 byte
  100   diem_x100[5]    5 x u16 = 10 byte
  110   du_tru[2]       2 byte, luon bang 0

Tong: 16 + n * 112 byte.

Truong du_tru khong dung toi hom nay, nhung no cho phep
them mot truong u16 o phien ban sau MA KHONG doi kich thuoc
ban ghi. Hai byte re hon mot lan doi dinh dang rat nhieu.

Chu y thu tu: trong TEP thi con_hoat_dong nam ngay sau
gioi_tinh, con trong BO NHO thi no nam o cuoi struct.
Hai bo cuc nay khac nhau, xem phan duoi.

#include <stdio.h>
#include <string.h>

#include "luutru.h"

#define MAGIC       "SVDB"
#define PHIEN_BAN   1u
#define CO_PHAN_DAU 16u
#define CO_BAN_GHI  112u

static int ghi_u16(FILE *f, uint16_t v) {
    unsigned char b[2] = { (unsigned char)(v >> 8), (unsigned char)v };

    return fwrite(b, 1, 2, f) == 2 ? 0 : -1;
}

static int ghi_u32(FILE *f, uint32_t v) {
    unsigned char b[4] = {
        (unsigned char)(v >> 24), (unsigned char)(v >> 16),
        (unsigned char)(v >>  8), (unsigned char)(v      ),
    };

    return fwrite(b, 1, 4, f) == 4 ? 0 : -1;
}

static int ghi_mot(FILE *f, const SinhVien *sv) {
    unsigned char du_tru[2] = { 0, 0 };

    if (fwrite(sv->mssv,   1, SV_MSSV_CO, f) != SV_MSSV_CO) return -1;
    if (fwrite(sv->ho_ten, 1, SV_TEN_CO,  f) != SV_TEN_CO)  return -1;
    if (fwrite(sv->lop,    1, SV_LOP_CO,  f) != SV_LOP_CO)  return -1;
    if (ghi_u16(f, sv->nam_sinh) != 0)                      return -1;
    if (fputc(sv->gioi_tinh,     f) == EOF)                 return -1;
    if (fputc(sv->con_hoat_dong, f) == EOF)                 return -1;

    for (int i = 0; i < SV_SO_MON; ++i)
        if (ghi_u16(f, sv->diem_x100[i]) != 0) return -1;

    return fwrite(du_tru, 1, 2, f) == 2 ? 0 : -1;
}

MaLoi lt_ghi_nhi_phan(const char *ten, const SinhVien *ds, size_t n) {
    char tam[512];

    int k = snprintf(tam, sizeof tam, "%s.tmp", ten);
    if (k < 0 || (size_t)k >= sizeof tam) return QL_LOI_GHI;

    FILE *f = fopen(tam, "wb");
    if (!f) return QL_LOI_MO_TEP;

    MaLoi kq = QL_LOI_GHI;

    if (fwrite(MAGIC, 1, 4, f) != 4)  goto xong;
    if (ghi_u32(f, PHIEN_BAN)  != 0)  goto xong;
    if (ghi_u32(f, (uint32_t)n) != 0) goto xong;
    if (ghi_u32(f, 0u)         != 0)  goto xong;    /* ma kiem, sua sau */

    uint32_t h = 2166136261u;

    for (size_t i = 0; i < n; ++i) {
        if (ghi_mot(f, &ds[i]) != 0) goto xong;

        h = ma_kiem_ban_ghi(&ds[i], h);
    }

    if (fseek(f, 12L, SEEK_SET) != 0) goto xong;
    if (ghi_u32(f, h) != 0)           goto xong;

    kq = QL_OK;

xong:
    if (fclose(f) != 0) kq = QL_LOI_GHI;

    if (kq != QL_OK) { remove(tam); return kq; }

    remove(ten);

    return rename(tam, ten) == 0 ? QL_OK : QL_LOI_GHI;
}