How to loop in Python

Python Lists

Python has some pretty powerful functionality to loop through any kind of Python list. The syntax to do so is simple:

for i in list:
    # do something

For example, consider the following:

Conventionally, in languages like C++ and Java, a variable is arithmetically changed upon every iteration of the loop. For example, in the following for loop, the variable i is incremented upon each iteration:

for(int i = 0; i < arr_length; i++)
{
    cout << i << endl;
}

In Python, however, a variable is set to an element in a given list upon every iteration.

The range() function

To achieve the functionality of conventional for-loop in Python, the range() function is used. It returns a list of integers. It works like so:

>> range(start,end)
>> [start, start+1, start+2..., end-1]

It can also be done in increments/decrements like so: