Example code of Regular Expression for form verification, detailed explanation of Regular Expression

Example code of Regular Expression for form verification, detailed explanation of Regular Expression

The regular expression for Form Verification is as follows:

First, I want to explain some symbolic meanings to you.

1./^ $/This is a common format.

^ Match the start position of the input string; $ match the end position of the input string

2. Enter the functions to be implemented.

* Matches the previous subexpression zero or multiple times;
+ Match the previous subexpression once or multiple times;
? Match the previous subexpression zero or one time;
\ D matches a numeric character, which is equivalent to [0-9]

The following code analyzes the Regular Expression and verifies the regular expression. The specific code is as follows:

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