python-doc/Docs/Basic/03-loops.md

1. Looping Through a List

list = [1, 2, 3, 5, 9, 'abbas']
for item in list:
    print(f'Item In List: {item}')

Explanation:

• A list is a collection of items in Python, enclosed in square brackets [].
• The for loop iterates over each element in the list.
• item is a variable that takes the value of each element in the list one by one.
• print(f'Item In List: {item}') uses an f-string to display the current item.

Output:

Item In List: 1
Item In List: 2
Item In List: 3
Item In List: 5
Item In List: 9
Item In List: abbas

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2. Looping Through a String

string = "abbas gholi"
for char_string in string:
    print(char_string)

Explanation:

• A string is a sequence of characters.
• The for loop iterates over each character in the string.
• char_string is a variable that holds each character in turn.
• Each character is printed on a new line.

Output:

a
b
b
a
s
 
g
h
o
l
i

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3. Looping Through a Dictionary

price = {
    "oil": 500000,
    "egg": 350000,
    "frute": {
        "apple": 100000,
        "orange": 120000
    }
}

This is a dictionary with:

• Keys: "oil", "egg", "frute"
• Values: numbers and another dictionary

Method 1: Looping Over Keys

for name in price:
    print(name, price[name])

Explanation:

• for name in price iterates over the keys of the dictionary.
• price[name] retrieves the value corresponding to the key.
• Prints each key and its value.

Output:

oil 500000
egg 350000
frute {'apple': 100000, 'orange': 120000}

Method 2: Using .items()

for name, pr in price.items():
    print(name, pr)

Explanation:

• .items() returns key-value pairs as tuples.
• name, pr unpacks each tuple into two variables.
• More efficient and readable than accessing price[name].

Output:

oil 500000
egg 350000
frute {'apple': 100000, 'orange': 120000}

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Summary

Concept	Description
List	Ordered collection of items. Use for item in list to iterate.
String	Sequence of characters. Use for char in string to access each character.
Dictionary	Key-value pairs. Use for key in dict or for key, value in dict.items() to loop.