正则表达式

• . means “any single character” except newline
• * zero or more of the preceding match
• + one or more of the preceding match
• [abc] any one character of a, b, and c
• (RX1|RX2) either something that matches RX1 or RX2
• ^ the start of the line
• $ the end of the line

实用工具/参考资料

• https://ihateregex.io/
• https://regex101.com/
• https://www.regular-expressions.info/
• https://emailregex.com/