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Dictionaries are commonly used to store and retrieve data using specific keys. In Python, dictionaries are equivalent to objects in JavaScript.


Design a program to store and retrieve personal information of students using a dictionary. The personal information includes name, age, and city.

JavaScript implementation

let personalInfo = {}; = 'luckrnx09';
personalInfo.age = 18; = 'Chengdu';


Python implementation

personal_info = {}

personal_info["name"] = 'luckrnx09'
personal_info["age"] = 18
personal_info["city"] = 'Chengdu'


Code Highlight

  • In both Python and JavaScript, you can use {} to create an empty dictionary/object.
  • In Python, you can only access values using square brackets (my_dict[key]), while in JavaScript, you can also use dot notation (myObj.key) to access values.

Difference Quick View

Define dictionarylet obj = {};
let obj = {key1: value1, key2: value2};
dict1 = {}
my_dict = {"key1": value1, "key2": value2}
Access valueobj[key];my_dict[key]
Access value or default valueobj[key] ?? defaultVal;my_dict.get(key, default_value)
Update valueobj[key] = newValue;my_dict[key] = newValue
Merge and updateobj={...obj,...anotherObj}my_dict.update(another_dict)
Delete key-value pairdelete obj[key];del my_dict[key]
Check if key existskey in obj;key in my_dict
Get all keysObject.keys(obj);my_dict.keys()
Get all valuesObject.values(obj);my_dict.values()
Get number of key-value pairsObject.keys(obj).length;len(my_dict)

When creating a dictionary using {} syntax in Python, the keys of the dictionary must be wrapped in quotes. Additionally, Python allows you to create a dictionary using the dict() function and provide initial key-value pairs without the need for quotes around the keys.

my_dict = dict(a=1, b=2, ...)