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A regular expression is a special sequence of characters that helps you easily check whether a string matches a pattern.

Python has added the re module since version 1.5, which provides Perl-style regular expression patterns.

The re module enables the Python language to have all the regular expression functions.

The compile function generates a regular expression object based on a pattern string and optional flag parameters. The object has a series of methods for regular expression matching and replacement.

The re module also provides functions that are exactly the same as those of these methods, which take a pattern string as their first argument.

This section focuses on python regular expression parameter substitution.

Replace dictionary data with regular expressions

Regular expression'\ $\ {. *\} 'corresponding to ${memberID}

Explanation:\ $escape replacement string $\ {escape replacement string {. Except for any single self-character * match * in\ n, the characters preceding the character zero or more times\} escape in the replacement string}

Dict = {"memberId": "${memberID}", "password": "123456", "loanId": "${loanId}", "amount": "- 100"} data = {"memberId": 10001, "loanId": 1} for param in dict: value = dict [param] if param in data.keys (): s = str (data [param]) newValue = re.sub ('\ $\ {. *\}', s, value) dict [param] = newValueprint (dict)

Extend:

Common rules for regular expressions

^ matches the beginning of a string, specifies what the string must begin and ends with a matching string, and specifies that the string ends with a character before $+ matches the previous character once or more times > = 1 {m} specifies the number of matching characters? Match the previous characters 0 or 1 times

Regular expressions are handled by the re module in python. The common methods of the re module are as follows:

Re.match (re rules, strings, modifiers): match from scratch. The match starts with the first character of the string, and if the first character does not match the rule, the match fails.

Re.search (re rules, strings, modifiers): match contains. Matching from the first character of the string is not required. As long as there is a match in the string that matches the rule, the match is successful.

Re.findall (re rules, strings, modifiers): put all matching characters in the list and return.

Re.sub (re rule, replacement string, replaced string, number of substitutions, modifier): match characters and replace.

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