🐍 综合练习：成绩 JSON 库

扩展：加删除、按分数排序后保存。

# ========================================
# 示例：JSON 文件存成绩
# 说明：读写 students.json
# ========================================
import json

FILE = 'students.json'

def load_all():
    try:
        with open(FILE, encoding='utf-8') as f:
            return json.load(f)
    except FileNotFoundError:
        return []

def save_all(data):
    with open(FILE, 'w', encoding='utf-8') as f:
        json.dump(data, f, ensure_ascii=False, indent=2)

def add(name, score):
    data = load_all()
    data.append({'name': name, 'score': score})
    save_all(data)

add('张三', 92)
add('李四', 88)
print(load_all())