Rust 字元is_alphabetic、is_alphanumeric概述 - 判斷是否為字母

Rust 字元is_alphabetic、is_alphanumeric概述 - 判斷是否為字母

  1月 16, 2024    LaGee

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字母判斷

判斷字元是否為字母有幾個方法

分別是is_alphabetic和is_alphanumeric

差別在於一個是單純判斷字母

另一個是可以額外判斷樹字

文件這樣解釋

is_alphabetic[1]

pub fn is_alphabetic(self) -> bool

is_alphabetic可以判斷字母

舉個例子

fn main() {

    let c_lowercase = 'a';

    let c_uppercase = 'Z';

    let c_digit = '5';

    let c_punctuation = '!';

   

    println!("Is alphabetic (lowercase): {}", c_lowercase.is_alphabetic());  

    println!("Is alphabetic (uppercase): {}", c_uppercase.is_alphabetic());  

    println!("Is alphabetic (digit): {}", c_digit.is_alphabetic());          

    println!("Is alphabetic (punctuation): {}", c_punctuation.is_alphabetic());    

}

Is alphabetic (lowercase): true Is alphabetic (uppercase): true Is alphabetic (digit): false Is alphabetic (punctuation): false

其中a和Z都是字母

因此輸出為true

但5和!不是

輸出false

is_alphanumeric[2]

pub fn is_alphanumeric(self) -> bool

is_alphanumeric可以判斷字母加上數字

也就是is_alphabetic和is_numeric[3]加起來

舉個例子

fn main() {

    let c_lowercase = 'a';

    let c_digit = '5';

    let c_punctuation = '!';

   

    println!("Is alphanumeric (lowercase): {}", c_lowercase.is_alphanumeric());

    println!("Is alphanumeric (digit): {}", c_digit.is_alphanumeric());

    println!("Is alphanumeric (punctuation): {}", c_punctuation.is_alphanumeric());

}

Is alphanumeric (lowercase): true Is alphanumeric (digit): true Is alphanumeric (punctuation): false

除了字母a會是true

數字5也會是true

驚嘆號則不是

其他語言

fn main() {

    let chinese = '校';

    let emoji = '💝';

   

    println!("Is alphanumeric (校): {}", chinese.is_alphabetic());

    println!("Is alphanumeric (校): {}", chinese.is_alphanumeric());

    println!("Is alphanumeric (💝): {}", emoji.is_alphabetic());

    println!("Is alphanumeric (💝): {}", emoji.is_alphanumeric());

}

Is alphanumeric (校): true Is alphanumeric (校): true Is alphanumeric (💝): false Is alphanumeric (💝): false

中文字也算是字母的一種

因此也會顯示true

但emoji不是

參考資料

[1] https://doc.rust-lang.org/std/primitive.char.html#method.is_alphabetic

[2] https://doc.rust-lang.org/std/primitive.char.html#method.is_alphanumeric

[3] https://doc.rust-lang.org/std/primitive.char.html#method.is_numeric