Basic valid integer
Input
parse_int_in_range(' 42 ', 0, 100)
Output
42
Whitespace is trimmed; 42 is within [0, 100].
Full lesson preview
Convert text to int with a range check
Safely parse a string to an integer and ensure it lies within a specified inclusive range.
Python practice15 minError Handling & Edge CasesIntermediateLast updated March 20, 2026
Problem statement
Implement parse_int_in_range(text, min_val, max_val) that:
- Accepts text (possibly with surrounding whitespace), min_val, and max_val (integers).
- Returns the integer value if text represents an integer in base 10 and min_val <= value <= max_val.
- Returns None for invalid conversions (non-integer text like '3.0', 'abc', empty string), or when the parsed integer is outside the inclusive range.
- Leading zeros and an optional leading '+' or '-' are allowed (e.g., '+0012' -> 12).
Be defensive: avoid raising exceptions for malformed input and ensure whole-string integer semantics (no partial parsing).
Task
Implement a conversion function that returns an integer when the text is a valid integer inside the given bounds, otherwise return None.
Examples
Input format
Three arguments: text (string), min_val (int), max_val (int).
Output format
Return parsed integer if valid and in range, otherwise return None.
Constraints
Do not use float conversions to detect integers. Ensure entire string (after strip) is an integer literal.
Samples
Sample 1
Input
parse_int_in_range('-5', -10, 0)
Output
-5
Negative values are supported and must be within the provided bounds.