[英]Smalltalk: how to check wether a string contains only numbers?
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. 所以基本上我有一些输入的可能性,用户应该只接受数字,否则将提醒用户他的输入不正确。
the input is considered a String when I read it out using a callback. 当我使用回调读出输入时,输入被视为字符串。 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. 现在我想检查字符串(应该包含数字)是否实际上只包含数字,但我没有找到已经实现的解决方案。 i tried 我试过了
theString isInteger
-is never true for the string - 字符串永远不会是真的
theString asNumber
- ignores letters, but I want to have a clear output wether letters are included in the string or not - 忽略字母,但我希望有一个清晰的输出字母是否包括在字符串中
theString isNumber
- always false - 总是假的
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: 您可以使用正则表达式来检查字符串是否仅包含数字:
theString matchesRegex: '\d+'
or a more complex regular expression to also allow an optional sign and decimal point: 或更复杂的正则表达式,以允许可选的符号和小数点:
theString matchesRegex: '-?\\d+(\\.\\d+)?'
Unfortunately, I could not locate messages ' isAllDigits
' or ' matchesRegex
'on Cincom Smalltalk
. 不幸的是,我无法在Cincom Smalltalk
上找到消息' isAllDigits
'或' matchesRegex
'。 However, what you could do is extract a word from the string and convert it to a number using asNumber
. 但是,您可以做的是从字符串中提取一个单词并使用asNumber
将其转换为数字。 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
. 因此,如果返回值为0(zero)
则表示该number
实际为0
(可以使用附加条件检查)或string
不包含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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