Programming Praxis

It’s mid-May, so at most universities the semester has ended and it is safe for me to solve some of the exercises that students sent to me over the last few months. Here’s a fun little one:

Given a string containing embedded numbers, find the sum of the embedded numbers. For instance, given the string “11aa22bb33cc44”, the desired sum is 11 + 22 + 33 + 44 = 110. You may not use regular expressions.

Although the problem statement doesn’t say so, you may assume that the numbers of interest are non-negative integers. Thus, the purpose of the exercise is for students to iterate through a string, identify the digits in the string, and manipulate them numerically.

Your task is to write a program that sums the numbers embedded in a string. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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