Implementation of regular expression matching strings

The most common use of regular expressions is to consider the implementation of regular expression matching judgment, in the actual work will often encounter what needs to match the string operation? Let's look at an example of an operation that implements a regular expression matching string.

Regular expression matches a string instance:

^[A-Za-z]+$

　 //匹配由26个英文字母组成的字符串

^[A-Z]+$

//匹配由26个英文字母的大写组成的字符串

^[a-z]+$

　 //匹配由26个英文字母的小写组成的字符串

^[A-Za-z0-9]+$

　 //匹配由数字和26个英文字母组成的字符串

^\w+$

//匹配由数字、26个英文字母或者下划线组成的字符串

Note: Some of the most basic and commonly used expressions

The regular expression matches the relevant content of the string to introduce you here, hoping to learn from you and learn to use regular expressions to match strings helps.