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From: | Jan-Peter Voigt |
Subject: | Re: Predicate for a string representing an integer |
Date: | Tue, 30 May 2017 11:13:21 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 |
Hi Urs,the functions used are built-in so I'd probably also do it (almost) that way. But I'd strongly recommend to test if obj is a string first:
#(define (integer-string? obj) (and (string? obj)(integer? (string->number obj))))Otherwise the predicate fails with an error (not false) if the argument is something else ... for example an integer. I doubt that checking all characters in the string are in the range '0'-'9' is faster then string->number.
Jan-Peter Am 30.05.2017 um 10:47 schrieb Urs Liska:
Hi all, I've found this function in my code: % Returns true if obj is a string representation of an integer #(define (integer-string? obj) (integer? (string->number obj))) and I have the impression there should be a better way with more built-in functionality to do it. Any suggestions, or should I simply leave it at that? Urs
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