Dictionaries in python

Dictionaries are useful to acess elemts using keys instead of keys,here keys are replaced by the index.

syntax:

variable_name = {

'key1' : 'element1',

'key2' : 'element',

...

'keyN' : 'elementN',

}

example:

roll = {

'alex' : '1WERG678',

'john' : '1WERG672',

'tom' : '1WERG666',

}

{'alex': '1WERG678', 'john': '1WERG672', 'tom': '1WERG666'}

Accessing element using keys

we cant use index positions for dicitiories, because they may vary, so we need to use keys for accessing the elemnts, If the specified key doesn’t exist, KeyError the exception will be raised.

roll["alex"]

'1WERG678'

Adding and Modifying elements

we can add or modify existing element by using this syntax given below

dict_name[key] = value

roll["jessy"]="1WERG645" #created new element

roll["alex"]="1WERG679" #roll no of alex is change to 79 to 78

Deleting Elements in dictionary

we can delete any element from the dictory by using del method ,If the key doesn’t exist in the dictionary, KeyError exception is raised.

del roll["alex"] #alex will be deleted

{'john': '1WERG672', 'tom': '1WERG666'}