[Leetcode] Valid Phone Numbers的筆記

Valid Phone Numbers

題目如下，大體就是給的電話號碼的格式只符合(xxx) xxx-xxxx or xxx-xxx-xxxx. (x爲數字)

Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.

You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)

You may also assume each line in the text file must not contain leading or trailing white spaces.

For example, assume that file.txt has the following content:

987-123-4567
123 456 7890
[phone]

Your script should output the following valid phone numbers:

987-123-4567
[phone]

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解題思路

• 這題不是非常的難，只需要用正則來匹配需要的格式顯示輸出就可以. 代碼如下:
  awk '/^(\([0-9]{3}\) ){1}[0-9]{3}-[0-9]{4}$|^([0-9]{3}-){2}[0-9]{4}$/' file.txt

• grep也有相似的功能, 那麼grep也可以進行輸出.
  -P 選項是利用PERL的正則語法進行匹配
  -o 是僅匹配這樣的模式
  grep -P '^(\([0-9]{3}\) ){1}[0-9]{3}-[0-9]{4}$|^([0-9]{3}-){2}[0-9]{4}$' file.txt
  上面的參數可以把-P變成-Po，結果也是被接受。

• sed也是可以匹配正則，那麼sed也是有它的答案
  sed -nr '/^(\([0-9]{3}\) ){1}[0-9]{3}-[0-9]{4}$|^([0-9]{3}-){2}[0-9]{4}$/p' file.txt
  

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