Thưa ông Gumby .' "Số Tập đoàn và các chức năng trong Substitutions" phần sau trong chương này để thông tin về làm thế nào để sử dụng chức năng này hiệu quả hơn. chức năng là một chức năng tiện ích được sử dụng để thoát khỏi | CHAPTER 10 BATTERIES INCLUDED 247 Or you could find the punctuation pat r . - pat text . -- . Note that the dash - has been escaped so Python won t interpret it as part of a character range such as a-z . The function is used to substitute the leftmost nonoverlapping occurrences of a pattern with a given replacement. Consider the following example pat name text Dear name . pat Mr. Gumby text Dear Mr. Gumby. See the section Group Numbers and Functions in Substitutions later in this chapter for information about how to use this function more effectively. The function is a utility function used to escape all the characters in a string that might be interpreted as a regular expression operator. Use this if you have a long string with a lot of these special characters and you want to avoid typing a lot of backslashes or if you get a string from a user for example through the raw_input function and want to use it as a part of a regular expression. Here is an example of how it works www .python .org But where is the ambiguity But where is the ambiguity Note In Table 10-9 you ll notice that some of the functions have an optional parameter called flags. This parameter can be used to change how the regular expressions are interpreted. For more information about this see the section about the re module in the Python Library Reference http doc lib . The flags are described in the subsection Module Contents. Match Objects and Groups The re functions that try to match a pattern against a section of a string all return MatchObject objects when a match is found. These objects contain information about the substring that matched the pattern. They also contain information about which parts of the pattern matched which parts of the substring. These parts are called groups. A group is simply a subpattern that has been enclosed in parentheses. The groups are numbered by their left .
