Simple positive number
Input
str_to_int('42')
Output
42
The string '42' converts to the integer 42.
Full lesson preview
Convert String to Integer
Convert a numeric string into an integer, handling optional whitespace and sign characters.
Python practice15 minVariables & Data TypesIntermediateLast updated December 29, 2025
Problem statement
Create a function that accepts a string representing an integer and returns its integer value. The input string may include leading or trailing whitespace and an optional '+' or '-' sign. You may assume the string represents a valid integer (no letters or decimal points). Do not print; return the integer.
Task
Write a function that converts a string containing an integer into a Python int.
Examples
Whitespace and negative number
Input
str_to_int(' -7 ')
Output
-7
Leading/trailing whitespace is ignored and the sign is preserved.
Input format
A single string argument is passed to str_to_int(s).
Output format
Return the integer value represented by the string.
Constraints
Input strings are guaranteed to represent valid integers. Use int() conversion and return the result.
Samples
Sample 1
Input
str_to_int('0')
Output
0
The string '0' converts to integer 0.