list1 = []
while True:
    print("""
=====================================
欢迎:
    1. 添加学生
    2. 查看学生
    3. 修改学生信息
    4. 删除学生
    5. 返回
=====================================
""")
    num = input('请选择(1-5):')
    if num == '1':
        while True:
            student = dict.fromkeys(['姓名', '年龄', '成绩', '电话'], None)
            for item in student:
                student[item] = input('请输入%s:' % (item))
            list1.append(student)
            print('添加成功')
            print('1.继续')
            print('2.返回')
            num = input('请输入:')
            if num == '1':
                student = student.copy()
                continue
            else:
                break
    elif num == '2':
        while True:
            print('1.查看所有学生')
            print('2.按姓名查找')
            print('3.按电话查找')
            print(('4.返回'))
            num = input('请输入:')
            if num == '1':
                    for item in list1:
                        name = item['姓名']
                        print(name)
            elif num == '2':
                while True:
                    name1 = input('请输入姓名:')
                    for item in list1:
                        if item['姓名']==name1:
                            print(item)
                    print('1.继续')
                    print('2.返回')
                    num3 = input('请输入:')
                    if num3 == '1':
                        continue
                    else:
                        break
            elif num == '3':
                while True:
                    tel1 = input('请输入电话号码:')
                    for item in list1:
                        if item['电话'] == tel1:
                            print(item)
                    print('1.继续')
                    print('2.返回')
                    num3 = input('请输入:')
                    if num3 == '1':
                        continue
                    else:
                        break
            elif num == '4':
                break
    elif num == '3':
        while True:
            name2 = input('请输入要修改信息的学生姓名:')
            for index in range(len(list1)):
                    if list1[index]['姓名']== name2:
                        for item in list1[index]:
                            list1[index][item] = input('请输入%s:' % item)
                            list1[index] = list1[index]
            print('修改成功!')
            print('1.继续')
            print('2.返回')
            num3 = input('请输入:')
            if num3 == '1':
                continue
            else:
                break
    elif num == '4':
        while True:
            name3 = input('请输入要删除学生的姓名:')
            for item in list1:
                if item['姓名'] == name3:
                    list1.remove(item)
            print('删除成功!')
            print('1.继续')
            print('2.返回')
            num3 = input('请输入:')
            if num3 == '1':
                continue
            else:
                break