python 字典 update

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# 数据 b = {1: {2: 2, 3: 3}} c = {21: {2: 2, 3: 3}} # 更新数据 d = b.update(c) # 验证 print(b.update(c)) print(d) print(b)<br><br>结果：

None
None
{1: {2: 2, 3: 3}, 21: {2: 2, 3: 3}}

 

从上可知update不反返回值