Python basics of string handling

Python string handling

String input:

my_string = raw_input("please input a word:")

String judgment:

(1) determine whether it is a pure letter

my_string.isalpha()

String search match:

(1) re

re regular expression instance 1: ^[\w_]*$

First, \w means match any word character including the underscore, equivalent to '[A-Za-z0-9_]'.

And then followed by a _.

Look again at the * sign: matches the previous subexpression zero or more times. For example, zo* can match "z" and "zoo". * is equivalent to {0,}.

Finally, $: indicates the end of the string, and there are no more characters.

So, what this expression means is to view this [w_] (any word character with an underscore, followed by an underscore) as a whole, appearing zero or more times!

import re

my_string = raw_input("please input a word:")

if re.match('^[a-zA-Z]$', my_string):
print "it is a word"
else:
print "it is not a word"

String transformation:

(1) convert the string to all lowercase letters.

my_string = my_string.lower()

(2) concatenate multiple strings at 1.

my_string = my_string + "abc"

(3) intercept part 1 of the string. This example removes the first and last character and intercepts the middle segment.

my_string = my_string[1:len(my_string)-1]

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