这是本人做的第一个实践项目，用的知识都是书上有的，没有很多很复杂的知识

同时因为没有学习 C语言图形方面的知识，所以界面做得很丑，暂时先这样吧

源文件：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "student.h"

void main()
{
    int num_order;
    char c; 
    
    num_order = msg();//输出相关信息,获取相关操作 
    
    while( num_order!=1 && num_order!=2 && num_order!=3)
    {
        printf("请重新输入正确参数:\n");
        scanf("%d",&num_order); 
    }
    
    switch( num_order )
    {
        case 1: from_file(0); break;//查询 
        case 2: input_(); break;//录入 
        case 3: from_file(1); break;//修改 
    }
    
    c = getchar();//用于接受上一个回车符 
    printf("\n是否执行其他操作？\n是/Y、否/N\n");
    c = getchar();
    while( c == 89 || c == 121 ) 
    {
        printf("请输入相关参数\n");
        scanf("%d",&num_order);
        switch( num_order )
        {
            case 1: from_file(0); break;//查询 
            case 2: input_(); break;//录入 
            case 3: from_file(1); break;//修改 
        }
        c = getchar();
        printf("\n是否执行其他操作？\n是/Y、否/N\n");
        c = getchar();
    }
    
}

Student.h 头文件：

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

int msg();//信息提示窗口
void input_();//录入相关信息
void save_files( struct Student_info *p );//保存内容至文件 
void print_( struct Student_info *p, int n );//输出内容到屏幕 
void from_file( int flag );//读取文件内容
void change_info( struct Student_info *p, int loop );//修改相关内容
void sort_info(struct Student_info *p);//排序 

struct Student_info
{
    char name[10];
    int id;
    int age;
    char adress[30]; 
};

int num_stud;

int msg()//信息提示窗口 
{
    int n;
        
    printf("\t\t\t\t学生管理系统\n\n");
    printf("\t\t  请输入你想执行的操作：\n");
    printf("\t\t ╭════════════════╮ \n");
    printf("\t\t║1.学生信息查询                    ║\n");
    printf("\t\t║2.学生信息录入                    ║\n"); 
    printf("\t\t║3.学生信息修改                    ║\n");
    printf("\t\t╰═════════════════╯\n"); 
    
    scanf("%d",&n);
    return(n);
}

void input_()//录入相关信息
{
    int i;
    struct Student_info *p,*into_save;
    
    system("cls");
    
    printf("学生信息录入系统：\n");
    printf("请输入想要录入信息的学生人数\n");
    
    scanf("%d",&num_stud);
    if((into_save = p = ( struct Student_info *)malloc( num_stud * sizeof( struct Student_info ))) == NULL )
        printf("创建空间失败！\n");
    else
        printf("依次输入学生学号 姓名  年龄  地址\n");
    for( i = 0; i < num_stud ; i++, p++ )
    {
        scanf( "%d %s %d %s", &p->id, p->name, &p->age, p->adress);
    }
    
    save_files( into_save );
}

void save_files( struct Student_info *p )//内容保存 
{
    int i;
    FILE *fp;
    if( (fp = fopen( "stud.dat", "ab" )) != NULL )
    {
        for( i = 0; i < num_stud; i++, p++ )
        {
            fwrite( p , sizeof(struct Student_info), 1, fp);
        }
        fclose( fp );
        printf( "信息录入完成！\n" );
    }
    else if( (fp = fopen( "stud.dat", "wb" )) == NULL )
    {
        printf( "文件创建失败！\n");
        exit(0);
    }
    else
    {
        for( i = 0; i < num_stud; i++, p++ )
        {
            fwrite( p , sizeof(struct Student_info), 1, fp);
        }
        fclose( fp );
        printf( "信息录入完成！\n" );
    }
}

void print_( struct Student_info *p, int n )//输出屏幕 
{
    int i;
    printf( "学号\t姓名\t年龄\t地址\n\n");
    for( i = 0; i < n ; i++, p++ )
    {
        printf( "%-4d %7s %6d %8s\n", p->id, p->name, p->age, p->adress);
    }
    printf("\n"); 
}

 void from_file( int flag )//读取文件内容 
{
    FILE *fp;
    struct Student_info temp;
    struct Student_info *p,*into_print,*first; 
    int i = 0;
    int loop = 0;
    
    system("cls");
    printf("\t学生信息查询   \n");
    
    if((fp = fopen("stud.dat","rb")) == NULL)
    {    
        printf( "文件信息不存在\n" );
        exit(0);
    }
    
    while( !feof(fp) )
    {    
        fread( &temp, sizeof(struct Student_info), 1, fp);
        loop++;
    }
    loop-=1;//获取文件中内容个数
    
    rewind(fp);
    first = into_print = p = (struct Student_info *)malloc(loop*sizeof(struct Student_info));     
    for( i = 0; i < loop; i++, p++ )
    {
        fread( p, sizeof(struct Student_info), 1 ,fp);
    }
    
    print_( into_print, loop ); 
    
    if( flag == 0 )
    {
        free( first );
        first = into_print = p = NULL;
    }
    else
    {
        change_info( first, loop ); 
    }
    fclose(fp);
}

void change_info( struct Student_info *p, int loop )
{
    int n,i;
    struct Student_info *t1,*t2;
    FILE *fp;
    
    printf("请输入要修改学生信息的学号:\n");
    scanf("%d",&n);
    t2 = t1 = p;
    
    for( i = 0; i < loop; i ++, t1++ )
    {
        if( t1->id == n)
            break;
    }
    scanf( "%d %s %d %s", &t1->id, t1->name, &t1->age, t1->adress);
    
    if( ( fp = fopen( "stud.dat", "wb") ) == NULL )
    {
        printf("文件写入错误！\n");
    }
    else
    {
         for( i = 0; i < loop; i ++, p++ )
         {
             fwrite( p, sizeof(struct Student_info), 1, fp );
         }
    }
    fclose(fp);
    printf("修改成功！\n");
    free(t2);
}