What is the principle of using for to iterate a dictionary in python?

Loop traversal of dictionaries, lists and other data is often used in development, but traversal of dictionaries in python is very unfamiliar to many beginners. Today we will talk about python There are two ways to loop through the dictionary.

1. Only traverse keys

A simple for statement can loop through all the keys of the dictionary, just like processing a sequence

2. Traverse both keys and values

If you only need values, you can use d.values. If you want to get all For keys, you can use d.keys.

If you want to get the key and value, the d.items method will return the key-value pair as a tuple. One of the benefits of the for loop is that you can use sequence unpacking in the loop.

Code example:

Note: The order of dictionary elements is usually not defined. In other words, when iterating, the keys and values ​​in the dictionary are guaranteed to be processed, but the processing order is uncertain. If order is important, you can save the key values ​​in a separate list, for example to sort before iterating.

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