Input Sanitization

Input Sanitization

Often you need to normalize the user’s input so that all input is either in
lower or upper case. Functions upper() and lower() do the job:
a = "PyTHon"
print a.upper()
print a.lower()
The print statements output ‘PYTHON’ and then ‘python’.
If you need to be sure that a string does not contain any leading
or trailing white space, use the strip() function. The following code
outputs the string ‘fancy message’:
a = " fancy message "
print a.strip()
This is actually one of the most often needed operations for strings – in
this book it is used in 12 examples. It is especially useful when you
receive data from a file or over a network connection.
You can replace a substring in a string with the function replace().
The following example outputs ‘Python is the future’:
a = "Java is the future"
print a.replace("Java", "Python")
You can also replace individual characters in a string, which is often
useful for cleaning up input, say, from a web service. The following
example removes all spaces in a string and outputs ‘1,2,3,4,5,6’.
a = " 1, 2, 3, 4, 5,6 "
print a.replace(" ", "")
If you need to cut a string into a list of substrings, use the function
split(). In default mode, split() cuts the string at every space
character. If you give a string parameter to split(), it is used as the
delimiter instead. The following example prints out the list ["one",
"two", "three", "four"].
txt = "one:two:three:four"
print txt.split(":")