BUPT-homework/semester1/pset14/2-4-database.c

#include <stdio.h>
#include <string.h>
#pragma GCC optimize("Ofast,inline")
#define MAX 11
#define CLASS 3

typedef struct STUDENT {
  char name[MAX];
  char id[MAX];
  int scores[CLASS];
} STUDENT;

int parser(int operation, STUDENT *students, int size);
int match(char *id, STUDENT *students, int size);
// Returns a location of students if found, else return -1

int add(char *id, char *name, int *scores, STUDENT *students, int size); // 1
int delete (char *id, STUDENT *students, int size);                      // 2
void update(char *id, int *scores, STUDENT *students, int size);         // 3
void display(char *id, STUDENT *students, int size);                     // 4

int main(void) {
  int operations;
  scanf("%d", &operations);

  STUDENT students[operations];

  int operation;
  int size = 0;
  for (int i = 0; i < operations; i++) {
    scanf("%d", &operation);
    size += parser(operation, students, size);
  }

  return 0;
}

int parser(int operation, STUDENT *students, int size) {
  if (operation == 1) {
    char id[MAX];
    char name[MAX];
    int scores[CLASS];
    scanf("%s%s", id, name);
    /* printf("id:%s, name:%s\n", id, name); */
    for (int i = 0; i < CLASS; i++) {
      scanf("%d", &scores[i]);
      /* printf("Score[%d]: %d\n", i, scores[i]); */
    }

    return add(id, name, scores, students, size);
  } else if (operation == 2) {
    char id[MAX];
    scanf("%s", id);

    return delete (id, students, size);
  } else if (operation == 3) {
    char id[MAX];
    int scores[CLASS];
    scanf("%s", id);
    for (int i = 0; i < CLASS; i++) {
      scanf("%d", &scores[i]);
    }

    update(id, scores, students, size);
    return 0;
  } else {
    char id[MAX];
    scanf("%s", id);

    display(id, students, size);
    return 0;
  }
}

int add(char *id, char *name, int *scores, STUDENT *students, int size) { // 1
  // returns if Students already exist
  if (match(id, students, size) != -1) {
    printf("Students already exist\n");
    return 0;
  }

  // Add data to the location "size"
  strcpy(students[size].id, id);
  strcpy(students[size].name, name);
  for (int i = 0; i < CLASS; i++) {
    students[size].scores[i] = scores[i];
  }
  printf("Add success\n");
  return 1;
}

int delete (char *id, STUDENT *students, int size) { // 2
  // Returns if student doesn't exist
  int loc = match(id, students, size);
  if (loc == -1) {
    printf("Students do not exist\n");
    return 0;
  }

  // Shift the array left.
  for (int i = loc; i < size - 1; i++) {
    students[i] = students[i + 1];
  }

  printf("Delete success\n");
  return -1;
}

void update(char *id, int *scores, STUDENT *students, int size) { // 3
  int loc = match(id, students, size);
  if (loc == -1) {
    printf("Students do not exist\n");
		return;
  }

  // Update the student
  for (int i = 0; i < CLASS; i++) {
    students[loc].scores[i] = scores[i];
  }
  printf("Update success\n");
}

void display(char *id, STUDENT *students, int size) { // 4
  int loc = match(id, students, size);
  if (loc == -1) {
    printf("Students do not exist\n");
		return;
  }

  // Display the average score
  int sum = 0;
  for (int i = 0; i < CLASS; i++) {
		/* printf("score[%d]: %d\n", i, students[loc].scores[i]); */
    sum += students[loc].scores[i];
  }
  printf("Student ID:%s\nName:%s\nAverage Score:%.1f\n", id, students[loc].name,
         (float)sum / CLASS);
}

int match(char *id, STUDENT *students, int size) {
  for (int i = 0; i < size; i++) {
    if (strcmp(id, students[i].id) == 0) { // matched
      return i;
    }
  }
  return -1;
}