Student achievement management system (C language linked list)

Functional requirements: input student scores, modify student scores, count the total and average scores of each student, sort according to the average scores of students, query student scores, and output student transcripts. Be able to save students' grades and read and write files. The interface is simple and easy to operate.

2, Main design ideas

The linked list is used as a data structure to store student scores and other information, and then a pile of functions are written around the linked list to realize a pile of functions

At the beginning of the program, the file data will be read to the linked list, and at the end, the information in the updated linked list will be rewritten to the file to save the data

3, Program source code and specific notes

(1) Preprocessing instruction

< stdlib. H > is imported because malloc function and free function are used

< string. H > is imported because the strcmp function is used

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define NAME_LEN 10
#define FILE_NAME "student grade. txt"

(2) Type definition

1.student type definition

A student variable represents a set of student information

typedef struct {
	char name[NAME_LEN + 1];//full name
	int number;				//Student number
	int chinese;			//chinese
	int math;				//mathematics
	int english;			//English
	int average;			//average
	int sum;				//Total score
} student;					//Used to store information about individual students

two studentNode type definition

A studentNode variable represents a student node

typedef struct node {
	student stu;		//Data field to store student information
	struct node *next;	//Pointer field, pointing to the next node
} studentNode;			//Student node

three studentList type definition

A studentList variable represents a student linked list

typedef struct {
	studentNode *head;	//Head pointer
	studentNode *tail;	//Tail pointer
	int count;			//Total number of student nodes
} studentList;			//Student list

(3) Function prototype

void initialize(studentList *L);//Initialize the list, create the header node
void enter(studentList *L);		//Enter linked list
void display(studentList *L);	//Output linked list
void find(studentList *L);		//Find a node
void modify(studentList *L);	//Modify a node
void sort(studentList *L);		//Rebuild the table in descending order and output
void write(studentList *L);		//Write files to free up space while writing
void read(studentList *L);		//Read files and create tables while reading

(4) main function definition

At the beginning, a linked list will be created and initialized, and then the information of the file will be read into the linked list

Interact with users through an infinite loop with a switch inside

At the end, the information in the linked list will be written to the file, and then the linked list will be destroyed

int main() {
	//Interactive interface
	printf("		**************Student achievement management system**************\n");
	printf("		*  1.Enter new student grades                      *\n");
	printf("		*  2.Modify student grades by name                    *\n");
	printf("		*  3.Query student scores by name                    *\n");
	printf("		*  4.Output the results of all students                    *\n");
	printf("		*  5.Output student scores by average                  *\n");
	printf("		*  6.Exit student achievement management system                  *\n");
	printf("		********************************************\n");
	printf("  	                                                \n");
	//Create student linked list
	studentList *L = (studentList *)malloc(sizeof(studentList));
	//Initialize student linked list
	initialize(L);
	//Read data from file to linked list
	read(L);
	//The interactive interface is written with an infinite loop and a switch
	while (1) {
		int code;
		printf("Please enter the number corresponding to the operation you want to perform: ");
		scanf("%d", &code);
		switch (code) {
			case 1:
				enter(L);
				break;
			case 2:
				modify(L);
				break;
			case 3:
				find(L);
				break;
			case 4:
				display(L);
				break;
			case 5:
				sort(L);
				break;
			case 6:
				write(L);
				free(L->head);	//The header node is destroyed
				free(L);		//The linked list was destroyed
				return 0;
			default:
				printf("%d Is an invalid number, please re-enter!\n\n", code);
				break;
		}
	}
	return 0;
}

(5) Other function definitions

1.initialize function definition

Receive a linked list pointer as a parameter

Create a head node without storing any information, and let the head and tail pointers of the linked list point to it

The initial length of the linked list is set to 0

void initialize(studentList *L) {
	//Create header node
	studentNode *s = (studentNode *)malloc(sizeof(studentNode));
	s->next = NULL;
	//Initialize linked list:
	//The head and tail pointers refer to the head node, and the initial length is zero
	L->head = s;
	L->tail = s;
	L->count = 0;
}

2. Definition of enter function

Receive a linked list pointer as a parameter

Let the user type information coexist in the new node

Insert the new node into the linked list

void enter(studentList *L) {
	//Create a new node
	studentNode *s = (studentNode *)malloc(sizeof(studentNode));
	//Type information into the new node
	printf("Please enter student name:");
	scanf("%s", s->stu.name);
	printf("Please enter student ID:");
	scanf("%d", &s->stu.number);
	printf("Please enter your language score:");
	scanf("%d", &s->stu.chinese);
	printf("Please enter your math score:");
	scanf("%d", &s->stu.math);
	printf("Please enter your English score:");
	scanf("%d", &s->stu.english);
	s->stu.sum = s->stu.chinese + s->stu.math + s->stu.english;
	s->stu.average = s->stu.sum / 3;
	//If the linked list is empty, point the tail pointer to the new node
	if (L->head == L->tail) {
		L->tail = s;
	}
	//Insert the new node into the head of the linked list (head insertion method)
	s->next = L->head->next;
	L->head->next = s;
	L->count++;
	//Output interactive information
	printf("Information entered successfully!\n\n");
}

3. Definition of display function

Traversing the linked list output is finished

void display(studentList *L) {
	printf("share%d Group student data:\n", L->count);
	printf("full name\t\t Student number\t\t chinese\t\t mathematics\t\t English\t\t Total score\t\t average\n");
	//Create a node pointer to the head node
	studentNode *p;
	p = L->head;
	//Traversal list output
	while (p->next) {
		p = p->next;
		printf("%s", p->stu.name);
		printf("\t\t%d", p->stu.number);
		printf("\t\t%d", p->stu.chinese);
		printf("\t\t%d", p->stu.math);
		printf("\t\t%d", p->stu.english);
		printf("\t\t%d", p->stu.sum);
		printf("\t\t%d", p->stu.average);
		printf("\n");
	}
	printf("\n");
}

4.find function definition

void find(studentList *L) {
	//Let the user enter the student to find
	printf("Please enter student name:");
	char name[NAME_LEN + 1];
	scanf("%s", name);
	//Traverse the linked list and compare names
	studentNode *p = L->head->next;
	while (p) {
		//If it matches, output and end the function
		if (strcmp(p->stu.name, name) == 0) {
			printf("full name\t\t Student number\t\t chinese\t\t mathematics\t\t English\t\t Total score\t\t average\n");
			printf("%s", p->stu.name);
			printf("\t\t%d", p->stu.number);
			printf("\t\t%d", p->stu.chinese);
			printf("\t\t%d", p->stu.math);
			printf("\t\t%d", p->stu.english);
			printf("\t\t%d", p->stu.sum);
			printf("\t\t%d", p->stu.average);
			printf("\n\n");
			return;
		}
		//If the name doesn't match, it's next
		p = p->next;
	}
	//I didn't find the name in the traversal
	printf("I didn't find this%s Information!\n\n", name);
}

5.modify function definition

void modify(studentList *L) {
	//Let the user enter the student to modify
	printf("Please enter student name:");
	char name[NAME_LEN + 1];
	scanf("%s", name);
	//Traverse the linked list and compare names
	studentNode *p = L->head->next;
	while (p) {
		//If yes, let the user retype and end the function
		if (strcmp(p->stu.name, name) == 0) {
			printf("Please re-enter the information:\n");
			printf("Please enter student ID:");
			scanf("%d", &p->stu.number);
			printf("Please enter your language score:");
			scanf("%d", &p->stu.chinese);
			printf("Please enter your math score:");
			scanf("%d", &p->stu.math);
			printf("Please enter your English score:");
			scanf("%d", &p->stu.english);
			p->stu.sum = p->stu.chinese + p->stu.math + p->stu.english;
			p->stu.average = p->stu.sum / 3;
			printf("Information modified successfully!\n\n");
			return;
		}
		//If the name doesn't match, it's next
		p = p->next;
	}
	//I didn't find the name in the traversal
	printf("I didn't find this%s Information!\n\n", name);
}

6. Definition of sort function

void sort(studentList *L) {
	//Neither node is in fart order
	if (L->count < 2) {
		printf("List sorting completed!\n");
		display(L);
		return;
	}
	//Insert sort
	studentNode *p, *pre, *tmp;
	//p points to the second student node
	p = L->head->next;
	//The linked list is disconnected from the head node and the first student node
	L->head->next = NULL;
	//Cycle back from the first student node
	while (p) {
		//Save the pointer of the next node
		tmp = p->next;
		//Find insertion location
		pre = L->head;
		while (pre->next != NULL && pre->next->stu.average > p->stu.average)
			pre = pre->next;
		//Update tail pointer
		if (pre->next == NULL) {
			L->tail = p;
		}
		//insert
		p->next = pre->next;
		pre->next = p;
		//Skip to next
		p = tmp;
	}
	printf("List sorting completed!\n");
	display(L);
}

7. Definition of write function

This function is used to save the information in the linked list to a file and destroy all nodes (except the head node)

void write(studentList *L) {
	//Open file flow
	FILE *fp = fopen(FILE_NAME, "w");
	if (fp == NULL) {
		printf("file%s Open failed\n", FILE_NAME);
		exit(EXIT_FAILURE);
	}
	//Output the total number of student nodes on the first line
	fprintf(fp, "%d\n", L->count);
	//Create a node pointer to the head node
	studentNode *p;
	p = L->head->next;
	//Traverse the linked list and output a set of data as a row
	while (p) {
		fprintf(fp, "%s ", p->stu.name);
		fprintf(fp, "%d ", p->stu.number);
		fprintf(fp, "%d ", p->stu.chinese);
		fprintf(fp, "%d ", p->stu.math);
		fprintf(fp, "%d ", p->stu.english);
		fprintf(fp, "%d ", p->stu.sum);
		fprintf(fp, "%d ", p->stu.average);
		fprintf(fp, "\n");
		//Free node space after output
		studentNode *next = p->next;
		free(p);
		p = next;
	}
	//Close file stream
	fclose(fp);
	//Interactive information
	printf("Data saved! Thanks for using. Bye!\n");
}

8. Definition of read function

This function is used to read the information in the file into the linked list and create nodes (except header nodes)

void read(studentList *L) {
	//Open file stream
	FILE *fp = fopen(FILE_NAME, "r");
	if (fp == NULL) {
		printf("file%s Open failed\n", FILE_NAME);
		exit(EXIT_FAILURE);
	}
	//Read the total number of student nodes in the first row
	fscanf(fp, "%d", &L->count);
	//The data is read circularly, and the number of cycles is count
	for (int i = 1; i <= L->count; i++) {
		//Create a new node
		studentNode *s = (studentNode *)malloc(sizeof(studentNode));
		//Read data
		fscanf(fp, "%s ", s->stu.name);
		fscanf(fp, "%d ", &s->stu.number);
		fscanf(fp, "%d ", &s->stu.chinese);
		fscanf(fp, "%d ", &s->stu.math);
		fscanf(fp, "%d ", &s->stu.english);
		fscanf(fp, "%d ", &s->stu.sum);
		fscanf(fp, "%d ", &s->stu.average);
		//Insert the new node into the tail of the linked list (tail insertion method)
		s->next = NULL;
		L->tail->next = s;
		L->tail = s;
	}
	//Close file stream
	fclose(fp);
}

4, Running example

Output all student scores

Enter a new set of data and close the program

The last entered information is still there, indicating that the information is saved successfully

5, Precautions

The file must be in the same directory as the source code

The file name is "student grade. txt"

Keywords: C linked list

Added by jllydgnt on Fri, 24 Sep 2021 17:41:32 +0300

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