Task 1 : 首字母大写
import re #python 正则表达式包：re s='hello world' s=re.sub(r"w+",lambda match:match.group(0).capitalize(),s)
赏析：
re.sub，实现正则的替换。
re.sub(pattern, repl, string, count=0, flags=0) Return the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by the replacement repl. If the pattern isn’t found, string is returned unchanged. repl can be a string or a function; if it is a string, any backslash escapes in it are processed. That is, is converted to a single newline character, is converted to a carriage return, and so forth. Unknown escapes such as j are left alone. Backreferences, such as 6, are replaced with the substring matched by group 6 in the pattern. For example: >>> >>> re.sub(r'defs+([a-zA-Z_][a-zA-Z_0-9]*)s*(s*):', ... r'static PyObject* py_1(void) {', ... 'def myfunc():') 'static PyObject* py_myfunc(void) {' If repl is a function, it is called for every non-overlapping occurrence of pattern. The function takes a single match object argument, and returns the replacement string. For example: >>> >>> def dashrepl(matchobj): ... if matchobj.group(0) == '-': return ' ' ... else: return '-' >>> re.sub('-{1,2}', dashrepl, 'pro----gram-files') 'pro--gram files' >>> re.sub(r'sANDs', ' & ', 'Baked Beans And Spam', flags=re.IGNORECASE) 'Baked Beans & Spam' The pattern may be a string or an RE object. The optional argument count is the maximum number of pattern occurrences to be replaced; count must be a non-negative integer. If omitted or zero, all occurrences will be replaced. Empty matches for the pattern are replaced only when not adjacent to a previous match, so sub('x*', '-', 'abc') returns '-a-b-c-'. In string-type repl arguments, in addition to the character escapes and backreferences described above, g<name> will use the substring matched by the group named name, as defined by the (?P<name>...) syntax. g<number> uses the corresponding group number; g<2> is therefore equivalent to 2, but isn’t ambiguous in a replacement such as g<2>0. 20 would be interpreted as a reference to group 20, not a reference to group 2 followed by the literal character '0'. The backreference g<0> substitutes in the entire substring matched by the RE. Changed in version 2.7: Added the optional flags argument.
Pattern : r"w+"表示匹配数字和字母下划线的多个字符。
repl : lambda match:match.group(0).capitalize()表示首字母大写。