so basically I have some input possibilities for the user where should only numbers be accepted, otherwise the user will be alerted his input was incorrect.
the input is considered a String when I read it out using a callback. now I want to check whether the string(which SHOULD contain numbers) actually DOES ONLY contain numbers, but I didnt find a solution implemented already. i tried
theString isInteger
-is never true for the string
theString asNumber
- ignores letters, but I want to have a clear output wether letters are included in the string or not
theString isNumber
- always false
在Squeak和Pharo中,您有#isAllDigits
消息,它可以完全满足您的需求:
'1233248539487523' isAllDigits "--> true"
You can use a regular expression to check that the string contains only numbers:
theString matchesRegex: '\d+'
or a more complex regular expression to also allow an optional sign and decimal point:
theString matchesRegex: '-?\\d+(\\.\\d+)?'
Unfortunately, I could not locate messages ' isAllDigits
' or ' matchesRegex
'on Cincom Smalltalk
. However, what you could do is extract a word from the string and convert it to a number using asNumber
. So, if the returned value is 0(zero)
it means that either the number
is actually a 0
(which could e checked with an additional condition) or string
did not contain a digit/number
.
这应该适用于许多Smalltalks方言:
(aString detect: [:c| c isDigit not ]) isNil ifTrue: [ "it's a number" ].
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