功能菜单：

1. 录入学生信息
2. 查找学生信息
3. 删除学生信息
4. 修改学生信息
5. 排序
6. 统计学生总人数
7. 显示所有学生信息
8. 退出系统

 

主函数流程

 

步骤流程图

1.录入学生信息

save(student) #用于将学生信息保存到文件
insert()函数，用于录入学生信息

2.查找学生信息

3.删除学生信息

4.修改学生信息

5.排序

6.统计学生总人数

7.显示所有学生信息

8.退出系统

代码：实现基本简单的学生管理系统

import os

filename = r'D:/casset/student.txt'
def main():
    while True:
        menu()
        choice = int(input("请选择一个数字："))
        if choice in range(8):
            if choice == 0:
                answer = input('您确定要退出吗:y/n')
                if answer == 'y' or answer == 'Y':
                    print('谢谢使用！！！')
                    break
                else:
                    continue
            elif choice == 1:
                
                insert()
            elif choice == 2:
                search()
            elif choice == 3:
                delete()
            elif choice == 4:
                modify()
            elif choice == 5:
                sort()
            elif choice == 6:
                total()
            elif choice == 7:
                show()
                          
def menu():
    print('=============学生信息管理系统==================')
    print('-----------功能菜单------------')
    print('\t\t\t\t\t\t\t\t\t1.录入学生信息')
    print('\t\t\t\t\t\t\t\t\t2.查找学生信息')
    print('\t\t\t\t\t\t\t\t\t3.删除学生信息')
    print('\t\t\t\t\t\t\t\t\t4.修改学生信息')
    print('\t\t\t\t\t\t\t\t\t5.排序')
    print('\t\t\t\t\t\t\t\t\t6.统计学生总人数')
    print('\t\t\t\t\t\t\t\t\t7.显示所有学生信息')
    print('\t\t\t\t\t\t\t\t\t0.退出系统')
    
def insert():
    student_list = []
    while True:
        id = input('请输入id:')
        if not id:
            break
        name = input('请输入姓名:')
        if not name:
            break
        try:
            english = float(input('请输入英语成绩:'))
            python = float(input('请输入python成绩:'))
            java = float(input('请输入java成绩:'))
        except:
            print('输入无效,不是成绩类型,请重新输入:')
            continue
        student = {'id':id, 'name':name, 'english':english, 'python':python, 'java':java}
        student_list.append(student)
        answer = input('是否继续录入:y/n')
        if answer == 'y':
            continue
        if answer == 'n':
            break
    save(student_list)
    print('录入完毕')
def save(lst):
    try:
        stu_txt = open(filename,'a',encoding='utf-8')
    except:
        stu_txt = open(filename,'w',encoding='utf-8')
    for item in lst:
        stu_txt.write(str(item)+'\n')
    stu_txt.close()
               
def search():
    student_query = []
    while True:
        id = ''
        name = ''
        if os.path.exists(filename):
            mode = input('若按id查找请输入1,如果按name查找请输入2:')
            if mode == '1':
                id = input('请输入要查找学生的id:')
            elif mode == '2':
                name = input('请输入要查找学生的name:')
            else:
                print('请重新输入指令:')
                search()
            with open(filename, 'r',encoding='utf-8')as rfile:
                student = rfile.readlines()
                for item in student:
                    d = dict(eval(item))
                    if id != '':
                        if d['id'] == id:
                            student_query.append(d)
                    elif name != '':
                        if d['name'] == name:
                            student_query.append(d)
            show_student(student_query)                      #显示查询结果
            student_query.clear()
            answer = input('是否要继续查找:y/n')
            if answer == 'y':
                continue
            else:
                break
        else:
            print('暂未保存学生信息')
            return
def show_student(lst):
    if len(lst)==0:
        print('未找到学生信息,数据无法显示!')
        return
    #定义标题显示格式
    format_title = '{:^6}\t{:^12}\t{:^10}\t{:^10}\t{:^10}\t{:^10}\t'
    print(format_title.format('id','姓名','英语成绩','python成绩','java成绩','总成绩'))
    #定义内容显示格式
    format_data = '{:^6}\t{:^14}\t{:^12}\t{:^10}\t{:^12}\t{:^14}\t'
    for item in lst:
        print(format_data.format(item['id'],
                                 item['name'],
                                 item['english'],
                                 item['python'],
                                 item['java'],
                                 float(item['english'])+float(item['python'])+float(item['java'])
                                 ))
def delete():
    while True:
        student_id = int(input('请输入要删除学生的id:'))
        if student_id != '':
            if os.path.exists(filename):                                    #        检查文件是否存在
                with open(filename,'r',encoding='utf-8')as file:
                    student_old = file.readlines()
            else:
                student_old = []
            flag = False                   #标记是否删除
            if student_old:
                with open(filename,'w',encoding='utf-8')as wfile:
                    d = {}
                    for item in student_old:
                        d = dict(eval(item))
                        if int((d['id'])) != student_id:
                            wfile.write(str(d)+'\n')
                        else:
                            flag = True
                    if flag:
                        print(f'id为{student_id}的学生信息已删除')
                    else:
                        print(f'未找到id为{student_id}学生的信息')
            else:
                print('无学生信息')
                break
            show()
            answer = input('是否继续删除:y/n')
            if answer == 'y' or answer == 'Y':
                continue
            else:
                break
def modify():
    show()
    if os.path.exists(filename):
        with open(filename,'r',encoding='utf-8')as rfile:
            student_old = rfile.readlines()
    else:
        return
    student_id = int(input('请输入您要修改的学生id:'))
    with open(filename,'w',encoding='utf-8')as wfile:
        for item in student_old:
            d = dict(eval(item))
            if int(d['id']) == student_id:
                print('找到学生信息,可以修改该学生信息')
                while True:
                    try:
                        d['name'] = input('请重新输入学生姓名:')
                        d['english'] = float(input('请重新输入英语成绩:'))
                        d['python'] = float(input('请重新输入python成绩:'))
                        d['java'] = float(input('请重新输入java成绩:'))
                    except:
                        print('输入有误,请重新输入:')
                    else:
                        break
                wfile.write(str(d)+'\n')
                print('修改成功！')
            else:
                wfile.write(str(d)+'\n')
        answer = input('您是否要继续修改:y/n')
        if answer == 'y' or answer == 'Y':
            modify()
        else:
            print('已返回初始界面!')    
def sort():
    show()
    if os.path.exists(filename):
        with open(filename,'r',encoding='utf-8')as rfile:
            students_list = rfile.readlines()
        students_new = []
        for item in students_list:
            students_new.append(eval(item))
    else:
        return
    asc_or_desc = input('请选择排序方式(0.升序 1.降序)')
    if asc_or_desc == '0':
        asc_or_desc_bool = False
    elif asc_or_desc == '1':
        asc_or_desc_bool = True
    else:
        print('输入错误,请重新输入：')
        sort()
    mond = input('请选择要排列的成绩:(0.总成绩 1.英语成绩 2.python成绩 3.java成绩):')
    if mond == '0':
        students_new.sort(key=lambda students_new : float(students_new['english'])+float(students_new['python'])+float(students_new['java']),reverse=asc_or_desc_bool)
    elif mond == '1':
        students_new.sort(key=lambda students_new : float(students_new['english']),reverse=asc_or_desc_bool)
    elif mond == '2':
        students_new.sort(key=lambda students_new : float(students_new['python']),reverse=asc_or_desc_bool)
    elif mond == '3':
        students_new.sort(key=lambda students_new : float(students_new['java']),reverse=asc_or_desc_bool)
    else:
        print('输入错误请重新输入')
        sort()
    show_student(students_new)
def total():
    if os.path.exists(filename):
        with open(filename,'r',encoding='utf-8')as rfile:  #检验文件是否存在
            students = rfile.readlines()
            if students:
                print(f'一共有{len(students)}名学生')
            else:
                print('没有录入学生信息')
    else:
        print('暂未保存数据信息')
def show():
    students_lst = []
    if os.path.exists(filename):
        with open(filename,'r',encoding='utf-8')as rfile:
            students = rfile.readlines()
            for item in students:
                students_lst.append(eval(item)) #将学生信息转换成字典保存在列表中
            if students_lst:
                show_student(students_lst)
            else:
                print('无录入信息')
    else:
        print('暂未保存数据信息')

if __name__ == '__main__':
    main()

修改完善

将已有功能封装在字典中，通过函数传递的功能实现调用（放在所有功能函数后）

func_dic = {'1':insert,'2':search,'3':delete,'4':modify,'5':sort,'6':total,'7':show}
def main():
    while True:
        menu()
        choice = input("请选择一个数字：")
        if choice == '0':
            answer = input('您确定要退出吗:y/n')
            if answer == 'y' or answer == 'Y':
                print('谢谢使用！！！')
                break
            else:
                continue
        elif choice in func_dic:
            func_dic[choice]()
        else:
            print("请输入正确的功能编号! ")
            continue

if __name__ == '__main__':
    main()