^ Of the Regular Expression

^ In a regular expression, it can be expressed as a negative or positioning character. See
Http://www.mifun.net/pengjie/myweb/article/article.asp? Id = 187 & sort = ASP

There is also a common operator in the regular expression, that is, the negative character "[^]". Unlike the positioning character "^" mentioned above, the "[^]" negative character specifies that the target object cannot contain strings specified in the pattern. Generally, when "^" appears in "[]", it is regarded as a negative operator. When "^" is located outside of "[]" or, it should be regarded as a positioning character.

"^ \ D + $" // non-negative integer (positive integer + 0)
"^ [0-9] * [1-9] [0-9] * $" // positive integer
Here I think it should be "^ [1-9] * [0-9] * $"
"^ (-\ D +) | (0 +) $" // non-positive integer (negative integer + 0)
"^-[0-9] * [1-9] [0-9] * $" // negative integer
"^ -? \ D + $ "// integer
"^ \ D + (\. \ D + )? $ "// Non-negative floating point number (Positive floating point number + 0)