用python写一个学生成绩管理系统，包括成绩录入，成绩显示，成绩查询，成绩排序（按总分），成绩修改，成绩统计，退出系统

好的，下面是一个简单的学生成绩管理系统的代码实现：

students = [] # 存储学生信息

# 添加学生信息
def add_student():
    name = input("请输入学生姓名：")
    math_score = int(input("请输入数学成绩："))
    english_score = int(input("请输入英语成绩："))
    chinese_score = int(input("请输入语文成绩："))
    total_score = math_score + english_score + chinese_score
    student = {"name": name, "math_score": math_score, 
               "english_score": english_score, "chinese_score": chinese_score, 
               "total_score": total_score}
    students.append(student)
    print("添加成功！")

# 显示学生信息
def show_students():
    if len(students) == 0:
        print("暂无学生信息！")
    else:
        print("姓名\t数学\t英语\t语文\t总分")
        for student in students:
            print(student["name"], "\t", student["math_score"], "\t", 
                  student["english_score"], "\t", student["chinese_score"], "\t", 
                  student["total_score"])

# 查询学生信息
def search_student():
    name = input("请输入要查询的学生姓名：")
    for student in students:
        if student["name"] == name:
            print("姓名\t数学\t英语\t语文\t总分")
            print(student["name"], "\t", student["math_score"], "\t", 
                  student["english_score"], "\t", student["chinese_score"], "\t", 
                  student["total_score"])
            return
    print("未找到该学生信息！")

# 按总分排序
def sort_students():
    students.sort(key=lambda x:x["total_score"], reverse=True)
    show_students()

# 修改学生信息
def modify_student():
    name = input("请输入要修改的学生姓名：")
    for student in students:
        if student["name"] == name:
            math_score = int(input("请输入数学成绩："))
            english_score = int(input("请输入英语成绩："))
            chinese_score = int(input("请输入语文成绩："))
            total_score = math_score + english_score + chinese_score
            student["math_score"] = math_score
            student["english_score"] = english_score
            student["chinese_score"] = chinese_score
            student["total_score"] = total_score
            print("修改成功！")
            return
    print("未找到该学生信息！")

# 统计学生信息
def statistics_students():
    math_total = 0
    english_total = 0
    chinese_total = 0
    for student in students:
        math_total += student["math_score"]
        english_total += student["english_score"]
        chinese_total += student["chinese_score"]
    print("总人数：", len(students))
    print("数学平均分：", math_total/len(students))
    print("英语平均分：", english_total/len(students))
    print("语文平均分：", chinese_total/len(students))

# 退出系统
def exit_system():
    print("感谢使用！")
    exit()

# 主函数
def main():
    while True:
        print("欢迎使用学生成绩管理系统！")
        print("1.添加学生信息")
        print("2.显示学生信息")
        print("3.查询学生信息")
        print("4.按总分排序")
        print("5.修改学生信息")
        print("6.统计学生信息")
        print("7.退出系统")
        choice = int(input("请输入您的选择："))
        if choice == 1:
            add_student()
        elif choice == 2:
            show_students()
        elif choice == 3:
            search_student()
        elif choice == 4:
            sort_students()
        elif choice == 5:
            modify_student()
        elif choice == 6:
            statistics_students()
        elif choice == 7:
            exit_system()
        else:
            print("输入有误，请重新输入！")

if __name__ == '__main__':
    main()

这个学生成绩管理系统支持添加学生信息、显示学生信息、查询学生信息、按总分排序、修改学生信息、统计学生信息、退出系统等功能。你可以根据自己的需要进行修改和扩展。