建立一个正规表达式来验证有效的电话号码.
规则表达式可以用来验证一个有效的电话号码,取决于特定的国家电话号码的特定格式和规则. 以下是一个规则表达式的例子,可以用来验证一个标准的美国电话号码的格式 (123) 456-7890: `^\(\d{3}\) \d{3}-\d{4}$` 这种规则表达式分为: - `^`声称字符串的开始位置. - `\`(与开头括号匹配. - `\d{3}`匹配一个数字 (等于 [0-9]) 3次. - `\) 匹配关闭括号. - 空间字符匹配一个单个空间. - `\d{3`}匹配一个数字 (等于 [0-9]) 恰恰3次. - `-匹配. - `\d]字符串的结尾符号 (或 4 `-d]) 可以按照不同的字符串的位置进行修改. - `\d\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\