Strings 15-112 Fundamentals of Programming 9/30/2013
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9/30/2013 Strings Strings are immutable 15-112 Fundamentals of Programming September 26th , 2013 String Functions s.count(sub) – Count the number of occurrences of sub in s name = “Daun Chuung" print name.count(“u") print name.count(“uu") Once created, a string itself cannot be changed You can assign a different string to an existing variables name = “Daun Chung" name.lower() print name name = name.lower() print name String Functions s.find(sub) Find the first index of sub in s, or -1 if not found name = “Yasser El-Sayed" print name.find(“El") print name.find(“ “) print name.find(“Yasser") print name.find(“yasser") 1 9/30/2013 String Functions s.index(sub) – find the first index of sub in s or error if not found name = “Yasser El-Sayed" print name.find(“El") print name.find(“ “) print name.find(“Yasser") print name.find(“yasser") String Functions s.split() – Returns a list of words in s name = “Muhammad Ali Najeeb Qazi" eachName = name.split() print eachName OUTPUT [‘Muhammad', ‘Ali', ‘Najeeb‘, ‘Qazi’] String Functions s.rfind(sub) – Find the last index of sub in s or -1 if not found s.rindex(sub) – Find the last index of sub in s or Error if not found String Functions s.join(lst) – Join the list of words into a single string using s as separator a = ["Harry", "Potter","and","the","goblet","of","fire"] t="" print t.join(a) Harry Potter and the goblet of fire t = “..” print t.join(a) Harry..Potter..and..the..goblet..of..fire 2 9/30/2013 What is HTML? Hyper Text Markup Language <HTML> <TITLE> Hello World </TITLE> <H1> Welcome to My Webpage </H1> How does the www work? You enter a URL in the address bar of your web browser The web browser fetches the index.html file from that location Index.html file has HTML code that is displayed by the web browser <img src="melatest.jpg“> </HTML> Reading webpages We can read web pages using Python We use the library called urllib Open a url by using urlopen p = urllib.urlopen("http://www.cnn.com") line = p.readline() while line: print line line = p.readline() Let’s Try this Read UPC barcode from user and display the item using http://www.upcdatabase.com import urllib upc = raw_input("Enter UPC> ") p = urllib.urlopen("http://www.upcdatabase.com/item/"+upc) line = p.readline() while line: if "Description" in line: line = line.replace("Description","") line = line.replace("<td>","") line = line.replace("</td>","") line = line.replace("<tr>","") line = line.replace("</tr>","") print line line = p.readline() 3
