Integer Range Checks in Python

Checking if an Integer Falls Within a Range

A common programming task is to determine if an integer value lies within a specific range. This is useful in various scenarios, such as validating user input, filtering data, or applying conditional logic based on numeric values. Python provides several clear and efficient ways to accomplish this.

Basic Comparison with and

The most straightforward approach is to use the and operator to combine two comparison expressions. This method explicitly checks if the number is greater than or equal to the lower bound and less than or equal to the upper bound.

number = 15000
lower_bound = 10000
upper_bound = 30000

if number >= lower_bound and number <= upper_bound:
    print("The number is within the range.")
else:
    print("The number is outside the range.")

In this example, the if statement evaluates to True only if both conditions – number >= lower_bound and number <= upper_bound – are met.

Python’s Chained Comparison

Python offers a more concise and readable way to express the same logic using chained comparisons. This is often considered the idiomatic Python way to check for a value within a range.

number = 15000
lower_bound = 10000
upper_bound = 30000

if lower_bound <= number <= upper_bound:
    print("The number is within the range.")
else:
    print("The number is outside the range.")

This code is equivalent to the previous example but is more compact and easier to read. Python evaluates the expression from left to right.

Performance Considerations

While both methods are generally efficient, chained comparisons might offer a slight performance advantage in some cases, though the difference is usually negligible for most applications. The dis module (disassembler) can show the bytecode differences, but it’s unlikely to be a significant factor in typical code.

Using range (Less Common for Single Value Checks)

The range function is typically used for generating sequences of numbers. While it can be used to check if a number is within a range, it’s generally less efficient for a single value check. It is better suited for checking if a number exists within a sequence of values.

number = 15000
lower_bound = 10000
upper_bound = 30000

if number in range(lower_bound, upper_bound + 1): # Note +1 to include the upper bound
    print("The number is within the range.")
else:
    print("The number is outside the range.")

Using range creates a sequence of numbers in memory, which can be less efficient than the direct comparison methods.

In most cases, the chained comparison (lower_bound <= number <= upper_bound) or the and operator approach (number >= lower_bound and number <= upper_bound) provides the most readable and efficient solution for checking if an integer falls within a specific range. Choose the approach that best suits your coding style and readability preferences.