How do I check if a char is an ASCII number or period?

user_13753914 0
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I would like to check whether a single char is an ASCII number ('1' - '9') or a period ('.'). What is the best way to do that in Rust? I know that is_digit(10) is for numbers but how do I do it for numbers or periods (.)?

rust character numbers validation ascii
2 Answers

One small catch of char::is_numeric might be that it matches on more than ASCII 0..=9, e.g:

'½'.is_numeric() == true

There's char::is_ascii_digit if you only want to match on ASCII 0..=9.

The latter is implemented with the matches! macro. You can also use the macro for your use case, e.g:

if matches!(c, '0'..='9' | '.') {
  // Character is ASCII digit '0' up to and including '9' or '.'
}
user_11139130

Use is_numeric OR'd with an '.' equality check:

fn is_numeric_or_period(c: char) -> bool {
    char::is_numeric(c) || c == '.'
}

Note: is_numeric matches all numeric unicode characters, and will behave identically to is_ascii_digit for ASCII strings, but if you're working with unicode strings and only want to match on ASCII numeric characters then refer to @Jason's answer.

user_27669080
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