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### Sum of integers in a string

Posted: Tue Jun 30, 2020 3:37 pm
A string consist of digits and non-digit characters. The digits contains a series of positive integers. For instance, the string “abc22zit62de0f” contains the integers 22, 62 and 0.
Write a function to calculate the sum of the integers inside a string (es. 22 + 62 + 0 = 84)

### Re: Sum of integers in a string

Posted: Wed Jul 01, 2020 3:23 am
Hi cameo,

my first attempt would be:

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``````(define (parse-str str)
(apply + (map int (clean empty? (parse str {[^0-9]} 0)))))``````
if it needs to be faster I would do:

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``````(define (parse-str str)
(let (total 0)
(dolist (s (parse str {[^0-9]} 0))
(unless (empty? s)
(inc total (int s))))
total))``````

### Re: Sum of integers in a string

Posted: Wed Jul 01, 2020 12:50 pm
Hi fdb,
Only a problem: numbers with leading 0 will convert in octal base.

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``Es. (parse-str "o123p010iru5") -> 136 (the correct value is 138)``
My function:

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``````(define (sum-str str)
(local (numeri expr)
(setq numeri '())
(setq expr {[0-9]+})
(replace expr str (push \$0 numeri -1) 0)
(apply + (map (fn (x) (int x 0 10)) numeri))
))
(sum-str "o123p010iru5")
;-> 138``````
best regards,
cameyo

### Re: Sum of integers in a string

Posted: Thu Jul 02, 2020 12:02 pm
In this case we could also do:

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``````> (apply + (map (fn (x) (int (if (starts-with x "0") (rest x) x))) (find-all {[0-9]+} "o123p010iru5")))
138``````

### Re: Sum of integers in a string

Posted: Thu Jul 02, 2020 4:27 pm
Nice, I didn't know starts-with and didn't know I could use a regex in find-all, but then we could also simplify your code:

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``````> (apply + (map int (find-all {[1-9][0-9]*} "o123p010iru5")))
138
>``````

### Re: Sum of integers in a string

Posted: Thu Jul 02, 2020 4:53 pm
Or replacing the map with a function for apply, so only traversing the string two times

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``````> (apply (fn(x y) (+ (int x) (int y))) (find-all {[1-9]\d*} "o123p0010iru5") 2)
138``````

### Re: Sum of integers in a string

Posted: Fri Jul 03, 2020 10:26 am
thank you. I learned new things.

### Re: Sum of integers in a string

Posted: Fri Jul 03, 2020 1:22 pm
cameyo wrote:
Fri Jul 03, 2020 10:26 am
thank you. I learned new things.
You're welcome! I learned new things too... :)