# 193.Valid Phone Numbers

**193.Valid Phone Numbers**

难度:Easy

> 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.

```
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
```

正则表达式：

```
# Read from the file file.txt and output all valid phone numbers to stdout.
cat file.txt | grep "^\(([0-9]\{3\}) \|^[0-9]\{3\}-\)[0-9]\{3\}-[0-9]\{4\}$"
```

> 执行用时 :0 ms, 在所有 C++ 提交中击败了100.00%的用户\
> 内存消耗 :3.1 MB, 在所有 C++ 提交中击败了52.82%的用户


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