Dict로 키-값 데이터 다루기

When you want to find a value by a name instead of a position, use a Dict. It maps keys to values. 🔑

A Dict declares two types: the key type and the value type, like Dict[String, Int].

Store a value by assigning through its key in brackets. This inserts the key-value pair into the dict.

Fetch a value by putting its key in brackets. The dict returns whatever you stored under that key.

Assigning to an existing key overwrites its value. Keys stay unique, so you never get duplicates.

Test whether a key exists with the in operator. It returns True or False without raising an error.

Count the pairs with len. It reports how many key-value entries the dict currently holds.

Looping a dict walks its keys. Use each key to reach its value inside the loop body.

Delete an entry with the pop method, passing the key. It removes the pair and returns its value.

A dict finds values fast because keys are hashable. Strings and Ints work great as keys.

Lookups, inserts, and updates are roughly constant time. That speed is why dicts power so much real code.

A Dict already has the key "Ada". You assign ages["Ada"] = 37. What happens to the dict size?

A Dict maps unique keys to values for fast lookup. Use brackets to set and get, in to check, and len to count. 🎯