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Python: Built-in Functions vs. For & If Loops – 5 Programs Explained

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Python’s built-in functions make coding fast and efficient. But understanding how they work under the hood is crucial to mastering Python. This post shows five Python tasks, each implemented in two ways: Using built-in functions Using for loops and if statements ✅ 1. Sum of a List ✅ Using Built-in Function: numbers = [ 10 , 20 , 30 , 40 ] total = sum (numbers) print ( "Sum:" , total) 🔁 Using For Loop: numbers = [ 10 , 20 , 30 , 40 ] total = 0 for num in numbers: total += num print ( "Sum:" , total) ✅ 2. Find Maximum Value ✅ Using Built-in Function: values = [ 3 , 18 , 7 , 24 , 11 ] maximum = max (values) print ( "Max:" , maximum) 🔁 Using For and If: values = [ 3 , 18 , 7 , 24 , 11 ] maximum = values[ 0 ] for val in values: if val > maximum: maximum = val print ( "Max:" , maximum) ✅ 3. Count Vowels in a String ✅ Using Built-ins: text = "hello world" vowel_count = sum ( 1 for ch in text if ch i...
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Python - How to Lookup Dictionary by Key

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Here's Python Dictionary that explained how to lookup it using Key. Dictionary in Python is Key/Value pair. It's different from the list. The basic rule to identify; is enclosed in flower brackets ({}). Here's a demo about lookup and how to test it. 


Dictionary = { 'key' : 'value', 'key: value'  }  


Dictionary Lookup


IN THIS PAGE

  1. Python Dictionary
  2. Python Lookup
  3. How to check Lookup working or not

Dictionary


Example

my_dict = {'name' : 'srini' , 'salary' : '100000', 'skills' : 'python' }

Here, 'name' is the label.

Then, :

Then, 'srini' -> Value

Explanation
  • Data is enclosed in flower brackets
  • It's an unordered list
  • You can manipulate data (mutable)
  • You can access the value of a particular key. So, in Python, it's called a Lookup. It's one of the best interview questions.



Lookup Dictionary by Key

Python Lookup (a.k.a Dictionary). You can access data quickly. It's really super-speed. 

my_dict['name']

The result will be: 'srini'

  • You should use square brackets ([]) to get lookup data
  • Use key-value in square brackets ([]) with a single quote, you will get value


Output from Lookup

I am now adding new value to the Lookup.

>>> my_dict['role'] = 'Manager'

Now, the my_dict will'be :

>>> my_dict = {'name' : 'srini' , 'salary' : '100000', 'skills' : 'python' , 'role' : 'Manager'}

  • The order of assignmenet will not match with actula storing in Python
  • The order of Key/Value storage is taken care by interpreter

References

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