11（3）. Through the structure and pointer to achieve a simple student management system (storage, sorting, output)

I insist on updating C Knowledge of language and data structure , Can collect ＋ Follow and keep abreast

Catalog

Code up

Realize the idea

Running results

Here we implement the most basic student management system , There is no chain storage , Instead, it uses a sequential storage structure , Structure used , The pointer , And dynamic memory allocation （ Dynamic memory allocation There is an update in my previous article ）.

Code up

#include <iostream>
#include <malloc.h>
#include <stdio.h>
using namespace std;
// void sort_student(struct *q, int len);
// Defining structure 
struct Student
{
    char name[20]; // full name 
    float score;   // fraction 
};
// Arrange students' grades according to the descending order of scores , Selective sorting is adopted 
void sort_student(struct Student *q, int len)
{
    for (int i = 0; i < len - 1; i++)
    {
        for (int j = i + 1; j < len; j++)
        {
            if ((q + i)->score < (q + j)->score)
            {
                struct Student temp; // Exchange student information 
                temp = *(q + i);
                *(q + i) = *(q + j);
                *(q + j) = temp;
            }
        }
    }
}
int main(int argc, char const *argv[])
{
    // cout << sizeof(struct Student) << endl;
    int len; // Define the number of students 
    cout << "please input the number of students:" << endl;
    cin >> len;
    struct Student *p = (struct Student *)malloc(sizeof(struct Student) * len);
    // We need to dynamically define an array to store structural variables , therefore p The type of must be struct Student, The memory required is （sizeof Student）*len;
    for (int i = 0; i < len; i++)
    {
        cout << "Please input N0." << i + 1 << "student information" << endl;
        cout << "Please input the name of student:" << endl; // Enter student name 
        cin >> (p + i)->name;
        // scanf("%s",p[i].name) name It's an array name , Itself is already the address of the first element of the array 
        cout << "Please input the score of student:" << endl;
        cin >> (p + i)->score;
    }
    sort_student(p, len); // Arrange the students in descending order of scores 
    // Output student information 
    cout << "--------------------The Student Score Information--------------------" << endl;
    for (int i = 0; i < len; i++)
    {
        cout << "name:" << (p + i)->name << "   score:" << (p + i)->score << endl;
    }
    cout << "---------------------------------------------------------------------" << endl;
    return 0;
}

Realize the idea

1. We define the structure struct Student;

2. Determine the number of students ,int len

3. According to the number of students , Dynamic memory allocation

        struct Student *p = (struct Student *)malloc(sizeof(struct Student) * len);

4. Use for Loop in student information

5. Write sorting function

        void sort_student(struct Student *q, int len)

6. Use for Loop out the sorted student information

Running results

  We can see , In the student information output , Output student information according to grade ranking