The `range` Function¶

Iteration over Numbers: `range()`¶

Rare: iteration using indexed access

Indexed access in C¶

char hello[] = "Hello World";
for (int i=0; i<sizeof(hello)-1; i++)
    printf("%d\n", hello[i]);

Rarely needed in Python
Iteration over data
If needed: sequence of integer numbers

hello = 'Hello World'
for i in range(len(hello)):
    print(ord(hello[i]))

`range()`: Definition ¶

The range() function produces numbers …

range(100) produces 0, 1, 2, ... 99
range(5, 100) produces 5, 6, 7, ... 99
range(5, 100, 2) produces 5, 7, 9, ... 99

Produces?

Result cannot easily be a list: range(10**9)

>>> type(range(10**9))
<class 'range'>

Generates numbers on demand
⟶ Generator

`range()`: Python 2 vs. Python 3 ¶

Incompatibility alert:

Python 2: range(10**9) would explode!
Heritage of the old Pre-Generator days
⟶ Python 2’s xrange() is a generator

If one wants a list in Python 3 (unlikely) …¶

l = list(range(10**9))