描述如何用Python编写一个简单的学生信息管理系统。
要编写一个简单的学生信息管理系统，可以遵循以下步骤：

1. 创建一个包含不同属性的Student类，如姓名、年龄、性别、学号和成绩等。

2. 在main方法中，创建一个列表来存储学生信息。

3. 根据用户的选择，编写增加、删除、更新和查找学生信息的函数。

4. 可以使用pickle模块来保存和加载学生信息。

5. 最后，编写一个循环程序，接收用户的输入，调用相应的函数，并输出结果。

以下是一个简单的Python代码示例：

```python
import pickle

class Student:
    def __init__(self, name, age, gender, student_id, grade):
        self.name = name
        self.age = age
        self.gender = gender
        self.student_id = student_id
        self.grade = grade

def add_student(students):
    name = input("Enter student name: ")
    age = int(input("Enter student age: "))
    gender = input("Enter student gender: ")
    student_id = int(input("Enter student id: "))
    grade = int(input("Enter student grade: "))
    student = Student(name, age, gender, student_id, grade)
    students.append(student)
    save_students(students)
    print("Student added successfully")

def delete_student(students):
    student_id = int(input("Enter student id to delete: "))
    for student in students:
        if student.student_id == student_id:
            students.remove(student)
            save_students(students)
            print("Student deleted successfully")
            return
    print("Student not found")

def update_student(students):
    student_id = int(input("Enter student id to update: "))
    for student in students:
        if student.student_id == student_id:
            name = input(f"Enter new name ({student.name}): ")
            age = int(input(f"Enter new age ({student.age}): "))
            gender = input(f"Enter new gender ({student.gender}): ")
            grade = int(input(f"Enter new grade ({student.grade}): "))
            student.name = name if name is not "" else student.name
            student.age = age if age is not None else student.age
            student.gender = gender if gender is not "" else student.gender
            student.grade = grade if grade is not None else student.grade
            save_students(students)
            print("Student updated successfully")
            return
    print("Student not found")

def search_student(students):
    student_id = int(input("Enter student id to search: "))
    for student in students:
        if student.student_id == student_id:
            print(f"Name: {student.name}")
            print(f"Age: {student.age}")
            print(f"Gender: {student.gender}")
            print(f"Student ID: {student.student_id}")
            print(f"Grade: {student.grade}")
            return
    print("Student not found")

def list_students(students):
    for student in students:
        print(f"Name: {student.name}")
        print(f"Age: {student.age}")
        print(f"Gender: {student.gender}")
        print(f"Student ID: {student.student_id}")
        print(f"Grade: {student.grade}")
        print("-----")

def save_students(students):
    with open("students.pickle", "wb") as f:
        pickle.dump(students, f)

def load_students():
    try:
        with open("students.pickle", "rb") as f:
            students = pickle.load(f)
    except FileNotFoundError:
        students = []
    return students

def main():
    students = load_students()
    while True:
        print("1. Add student")
        print("2. Delete student")
        print("3. Update student")
        print("4. Search student")
        print("5. List students")
        print("6. Exit")
        option = int(input("Enter your choice: "))
        if option == 1:
            add_student(students)
        elif option == 2:
            delete_student(students)
        elif option == 3:
            update_student(students)
        elif option == 4:
            search_student(students)
        elif option == 5:
            list_students(students)
        elif option == 6:
            break
        else:
            print("Invalid option")

if __name__ == "__main__":
    main()
```

以上代码使用pickle模块将学生信息保存到一个二进制文件中，以便在下一次运行程序时加载这些信息。可以在菜单中选择增加、删除、更新、查找或列出学生。