python3 字典基本函数实现

info = {'stu1':'one','stu2':'two','stu3':'there'}#print(info)print(info['stu2'])#取出key为stu2的值info['stu4'] = 'four'#增加字典容量del info['stu1']#删除   info.pop("stu1")print(info)if info.get('stu5') ==  None:print("None")else:print(info['stu5'])#判断元素是否在字典内if 'stu2' in info:print('YES')else:print('NO')#同样为判断是否存在print(info.keys())print(info.values())print(info.setdefault('stu5', 'five'))#若原字典存在，则不做改动，不存在，则赋予新值（无返回值）new = {'stu3':'233','233':'466'}info.update(new)#合并更新print(info)print(info.items())#转成列表d = dict.fromkeys([1, 2, 3, 4, 5], 'none')#列表初始化print(d)for key in info:#循环字典，较为高效print(key, info[key])for i, v in info.items():#循环字典，数据量大时较为低效print(i, v)

输出结果如下图：