Some methods of string!
1.text.endswith (". jpg") returns the value TRUE if the string is terminated with the given substring.
2. Text.upper (): Returns a copy of a string that is converted to all uppercase letters.
3.text.lower (): Returns a copy of a string that is converted to a full lowercase letter.
4.text.replace ("Tomorrow", "Tuesday"): Returns a copy of a string in which a substring is completely replaced with another substring.
5.text.strip (): Returns a copy of the string that removes the opening and trailing spaces.
6. Text.find ("Python"): Returns the first character index value of a substring when a given substring is found.
7.text.startswith ("<HTML>") returns True if the string starts with a given substring.
8.TEXT[A,B] takes a substring of the string that begins with the a index value to the end of the B index value but does not include the character corresponding to the B index value.
Import Urllib.requestpage=urllib.request.urlopen ("http://www.baidu.com") Text=page.read (). Decode ("UTF8") print ( Text
After adding a method to take out the substring
Import Urllib.requestpage=urllib.request.urlopen ("http://www.baidu.com") Text=page.read (). Decode ("UTF8") price= Text[234:238]print (Price)
where "#293的索引值分别为: 234,235,236,237,238 But the result of the above code is:
Remove substring after a given substring
Import Urllib.requestpage=urllib.request.urlopen ("http://www.baidu.com") Text=page.read (). Decode ("UTF8") where= Text.find (' = "') start_of_price=where+2end_of_price=start_of_price+4price=text[start_of_price:end_of_price]print (Price)
The type converted to float after the specific character is removed is compared to 4.47 if it is less than 4.47 and outputs: buy!
Import urllib.requestprice=99.99while price>4.47: page=urllib.request.urlopen ("http://www.baidu.com") Text=page.read (). Decode ("UTF8") where=text.find (' = "') start_of_price=where+2 end_of_price= Start_of_price+4 price=float (Text[start_of_price:end_of_price]) print ("buy!")Python's built-in time library
Python Library Documentation: Time
Time.clock () represents the current time in seconds, using the floating-point number format.
Time.daylight () If you are not currently in daylight saving time, return 0.
Time.gmtime () gives the current date and time of the UTC time (not affected by your time zone!). ）。
Time.localtime () gives the current local time (this is affected by your time zone).
Time.sleep (secs) rests within a given number of seconds, and does nothing.
Time.time () gives the number of seconds from January 1, 1970 to the current count.
Time.timezone () gives the number of hours between your time zone and the UTC (London) time zone.
Import Urllib.requestimport timeprice=99.99while price>4.47: time.sleep (page=) Urllib.request.urlopen ("http://www.baidu.com") Text=page.read (). Decode ("UTF8") where=text.find (' = ') start_of_price=where+2 end_of_price=start_of_price+4 price=float (text[start_of_price:end_of_price ]) print ("huy!")
Summarize
s represents a string.
S[4] Gets the 5th character in the S string.
S[6:12] Gets a substring in the string s. (Until the index value is 12 characters, but not included!)
S.find () is used to search for strings.
S.upper () Converts the string to all uppercase letters.
Float () Converts a string to a number with a decimal fraction, which is a floating-point.
+ "Addition" operator
> "Greater than" operator
Urllib. The request library is used to communicate with the Web
The time library is used for work related to dates/times!
Python's text data
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