For Loop Examples

Range Function

The range() function in Python is a built-in function that generates a sequence of numbers. It’s commonly used in loops to iterate a specific number of times.

Syntax:

range(stop)
range(start, stop[, step]])

• stop: The ending number (exclusive). The sequence will go up to, but not include, this number. This is the only required argument.
• start: The starting number (inclusive). Defaults to 0 if not specified.
• step: The increment between each number. Defaults to 1 if not specified. Can be negative for reverse iteration.

Examples:

# Basic usage:
for i in range(5):  # iterates 0, 1, 2, 3, 4
    print(i)

# Specifying start and stop:
for i in range(2, 7): # iterates 2, 3, 4, 5, 6
    print(i)

# Specifying start, stop, and step:
for i in range(1, 10, 2): # iterates 1, 3, 5, 7, 9
    print(i)

# Negative step:
for i in range(10, 0, -1): # iterates 10, 9, 8, 7, 6, 5, 4, 3, 2, 1
    print(i)

#Creating a list from range:
my_list = list(range(1,6)) # Creates 1, 2, 3, 4, 5
print(my_list)

Important Considerations:

• range() returns a range object, not a list. This is a memory-efficient way to represent a sequence of numbers, especially when dealing with large ranges. To get a list, you need to explicitly convert it using list().
• The stop value is always exclusive. This is a common source of off-by-one errors.

Range Object (Iteration in Python)