193. Valid Phone Numbers

Valid Phone Numbers

Problem Description

Given a text file file.txt that contains a 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.

Example:

Assume that file.txt has the following content:

987-123-4567
123 456 7890
(123) 456-7890

Your script should output the following valid phone numbers:

987-123-4567
(123) 456-7890

Solution

grep -E '(^[0-9]{3}-|^\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$' file.txt

Idea:

The construction is as follows

• ^: indicates the starting of the string
• |: or
• $: indicates the end of the string
• [0-9]{3} : represent 3 numbers ({3}) between the range 0-9 ([0-9] a digit in the range)
• : suppresses the specialness of the character
• -E: to include multiple regex

Conclusion

That’s all folks! In this post, we solved LeetCode problem #193. Valid Phone Numbers

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You can find the complete source code on my GitHub repository. If you like what you learn. feel free to fork 🔪 and star ⭐ it.

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