c - 学生数据库管理系统

Question

我正在创建一个小型 DBMS，用于记录学生姓名、 Material #、部门和专业。

我使用文本文件作为数据库；我的程序应该添加新学生、搜索学生、删除学生、更新学生信息等。目前，我正在将学生信息添加到数据库中并且工作正常，但我想要的是不断添加学生而无需再次运行程序，直到我按一个键。

所以，我使用了一个循环(同时执行 while 循环和 while 循环)并且它工作正常，但我无法将它们附加到数据库中。我不知道出了什么问题。

如果我不使用循环，它会将其附加到数据库，但如果我使用循环，它不会附加它。

/*
 * Files.c
 *
 *  Created on: Mar 2, 2015
 *      Author: ousainou
 */

    # include <stdio.h>
    # include <stdlib.h>

    void appending();
    void readFile();


    main()
    {

        //printf("do you want to add a student[y/n]");
         printf("*********************************\n");
         printf("*Students Management System(SMS)*\n");
         printf("*********************************\n");
        printf("press '1' to add a new student\n");
        printf("press '2' to view all students records\n");
        //frintf("press '3' to view a a student's information");
        //printf("press '4' to edit a student's infomation);
        //printf("press '5' to delete a student);
        int input;
        scanf("%d",&input);
        int x= 0;
        do{
        //do{
        if(input == 1)
        {
        appending();
        }
        else if(input == 2)
        {
            readFile();
        }
        printf("press -1 to exit");
        scanf("%d",&input);
        if(input == -1)
            break;

        }while(x == 0);
}
            int input;

            char firstname[20];

            char lastname[20];

            char mat_number[10];

            char department[10];

            char major[20];
            char read;
            int num = 1;
            int count = 0;

    void appending()
    {
        FILE*file = fopen("new file.txt","a");

        printf("enter first name\n");
        scanf("%s", firstname);

        printf("enter second name\n");
        scanf("%s", lastname );

        printf("enter mat number\n");
        scanf("%s", mat_number);

        printf("enter department\n");
        scanf("%s", department);

        printf("enter major\n");
        scanf("%s", major);

        fprintf(file,"\t\t%s\t\t%s\t\t%s\t\t%s\t\t%s\n",firstname,lastname,mat_number,department,major);
        if(file)
                {
                    printf("%s %s%s",firstname,lastname,"'s information has been stored\n");
                }
                else
                {
                    printf("database not found ");
                }

    }

    void readFile()
    {

            FILE*rfile = fopen("new file.txt","r");


        if(!rfile)
                {
                    printf("file not found");
                    exit(-1);
                }
                else
                {
                    do{
                        read = fgetc(rfile);

                        printf("%c",read);

                        }while(read != EOF);

                }


    }

Answer 1

您需要关闭文件，一旦打开您可以连续写入，但它不会在您的读取函数上读取新值(因为它作为新文件打开)。阅读后，您可能不需要保持文件打开。使用fclose()

/*
 * Files.c
 *
 *  Created on: Mar 2, 2015
 *      Author: ousainou
 */

    # include <stdio.h>
    # include <stdlib.h>

    void appending();
    void readFile();


int main()
    {

        //printf("do you want to add a student[y/n]");
         printf("*********************************\n");
         printf("*Students Management System(SMS)*\n");
         printf("*********************************\n");

        do{ 
            printf("press '1' to add a new student\n");
            printf("press '2' to view all students records\n");
            printf("press -1 to exit");
        //frintf("press '3' to view a a student's information");
        //printf("press '4' to edit a student's infomation);
        //printf("press '5' to delete a student);
        int input;
        scanf("%d",&input);
        //do{
        if(input == 1)
        {
        appending();
        }
        else if(input == 2)
        {
            readFile();
        }
        else if(input == -1)
        {
            break;
        }

        }while(true);
}

            int input;

            char firstname[20];

            char lastname[20];

            char mat_number[10];

            char department[10];

            char major[20];
            char read;
            int num = 1;
            int count = 0;

    void appending()
    {
        FILE* file = fopen("new file.txt","a");

        printf("enter first name\n");
        scanf("%s", firstname);

        printf("enter second name\n");
        scanf("%s", lastname );

        printf("enter mat number\n");
        scanf("%s", mat_number);

        printf("enter department\n");
        scanf("%s", department);

        printf("enter major\n");
        scanf("%s", major);

        fprintf(file,"\t\t%s\t\t%s\t\t%s\t\t%s\t\t%s\n",firstname,lastname,mat_number,department,major);
        if(file)
                {
                    printf("%s %s%s",firstname,lastname,"'s information has been stored\n");
                    fclose(file);
                }
                else
                {
                    printf("database not found ");
                }

    }

    void readFile()
    {

            FILE* rfile = fopen("new file.txt","r");


        if(!rfile)
                {
                    printf("file not found");
                    exit(-1);
                }
                else
                {
                    do{
                        read = fgetc(rfile);

                        printf("%c",read);

                        }while(read != EOF);
                    fclose(rfile);
                }


    }