Position of Difference X28758

Statement

Design a function @pos_dif(r, s)@ that, given two strings $r$ and $s$ , returns the first position at which $r$ and $s$ are different. If $r$ and $s$ are equal, the function must return $-1$ .

Sample session

>>> pos_dif('pero', 'peros')
4
>>> pos_dif('alaska', 'alaska')
-1
>>> pos_dif('caramba', 'calabaza')
2
>>> pos_dif('alas', 'ala')
3

Information

Author: InfBesos
Language: English
Translator
Original language: Catalan
Other languages: Catalan Spanish
Official solutions: Python
User solutions: Python