python - summary with code on Python string ess...
In this post, we are going to examine the string essentials. in this post, we are going to discuss the topic on the string class on the following aspects.
- Strings as sequence of characters
- Basic string operation
- Special characters and escape sequences
- Numeric (octal and hexadecimal) and Unicode escape sequences
- string methods
- split and join
- converting strings to numbers
- strip
- search
- modifying
- Useful methods and constants
- converting from objects to string
- Using the format method
the code is as follow.
'''
Created on 2012-10-28
@author: Administrator
file: StringEssentials.py
description: StringEssentials.py shows essentials on the string
Strings as sequence of characters
Basic string operation
Special characters and escape sequences
Numeric (octal and hexadecimal) and Unicode escape sequences
string methods
split and join
converting strings to numbers
strip
search
modifying
Useful methods and constants
converting from objects to string
Using the format method
'''
def string_as_list():
x = 'Goodby\n'
x = x[:-1]
print("*** string as list, chop")
print(x)
y = len("Goodby\n")
print("*** len(string)")
print(y)
def basic_string():
x = "Hello " + "World"
print("*** basic_string")
print(x)
def numeric_oct_hexadecimal_unicode_escape_sequence():
print("*** normal string notation")
x = 'm'
print(x)
print("*** octal notation")
y = '\155'
print(y)
print("*** hexadecimal noation")
y = '\x6D'
print(y)
# Because all string in Python3 are Unicode strings, they can also contain almost every character from
# every language avaiable.
# below show english name notation of Unicode
print("*** named unicode notation")
unicode_a = '\N{LATIN SMALL LETTER A}'
print(unicode_a)
unicode_a_with_acute = '\N{LATIN SMALL LETTER A WITH ACUTE}'
print(unicode_a_with_acute)
print("*** unicode with number Unicode")
unicode_a_with_acute_number= "\u00E1"
print(unicode_a_with_acute_number)
def print_evaluate_string_with_special_character():
print("*** print adds a newline to the end of the string")
print("abc\n")
print("*** end = \"\" cause the print NOT to append the newline")
print("abc\n", end = "")
def string_method_split_join():
print("*** str.join(...)")
x = " ".join(["join", "puts", "spaces", "between", "elements"])
print(x)
x = "::".join(["Separated", "with", "colons"])
print(x)
x = "".join(["Separated", "by", "nothing"])
print(x)
# default, the split method will split on any whitespace
x = 'You\t\t can have tabs\t\n \t and newlines \n\n ' \
"mixed in"
y = x.split()
print("*** str.split()")
print(y)
y = "Mississippi"
x.split("ss")
x = 'a b c d'
y = x.split(' ', 1) # you can tell how many times split happens in the second argument
def string_convert_to_numbers():
y = float('123.456')
try:
x = float('xxyy')
except ValueError:
pass
y = int('3333')
try:
int('123.333')
except ValueError:
pass
# you can change the radix of the expression
y = int('10000', 8)
def strip_string():
print("*** strip()")
x = " Hello, World\t\t "
y = x.strip()
print(y)
print("*** lstrip()")
y = x.lstrip()
print(y)
print("*** rstrip()")
y = x.rstrip()
print(y)
def string_module_constants():
import string
print("*** string constants")
print(string.whitespace)
def string_searching():
x = "Mississippi"
y = x.find("ss")
print("*** str.find()")
print(y)
y= x.rfind("ss")
print("*** str.rfind()")
print(y)
x = "Mississippi"
y = x.count("ss")
print("*** str.count()")
print(y)
y = x.startswith("Miss")
print("*** str.startswith")
print(y)
y = x.endswith("pi")
print("*** str.endswith()")
print(y)
y = x.endswith(("i", "u"))
def string_replace():
x = "Mississipi"
x.replace("ss", "+++")
print("*** str.replace")
x ="~x & (y % z)"
table= x.maketrans("!*()", "!&[]")
x.translate(table)
print("*** maketrans")
print(x)
def methods_and_constants():
x = "123"
print("*** isdigit")
print(x.isdigit())
print("*** isalpha")
print(x.isalpha())
x = "M"
print("*** islower")
print(x)
print("*** issupper")
print(x)
def convert_from_object_to_string():
x = repr([1,2,3])
print("*** repr")
print(x)
x = str([1, 2, 3])
print("*** str")
print(x)
def string_format():
x = "{{Ambrosia}} is the {0} of {1}".format("food", "The gods")
print("*** str.format")
print(x)
x = "{{Ambrosia}} is the {food} of {user}".format(food = "Ambrosia", user="the gods")
print("*** str.format with name arguments")
print(x)
x = "{0} is the food of {user[1]}".format("Ambrosia", user = ["men", "the gods", "others"])
print("*** str.format with name arguments")
print(x)
# advanced use of Format specified
x = "{0:{1}} is the food of gods".format("Ambrosia", 10)
print(x)
x= "{0:{width}} is the food of gods".format("Ambrosia", width = 10)
print(x)
# >width is left justification
x = "{0:>10} is the food of gods".format("Ambrosia")
print(x)
# <width is the right justification
x = "{0:&<10} is the food of gods".format("Ambrosia")
print(x)
# besides the C# style of format, it also supports the C style format
x = "%s is the %s of %s" % ("Ambrosia", "food", "The gods")
print(x)
num_dict = {'e': 2.718, 'pi': 3.14159}
print("%(pi).2f - %(pi).4f - %(e).2f" % num_dict) # not that the name is in parenthesis
def control_print():
#print, override the end separator
print("a", "b", "c", end="\n\n")
#print , override the default sep
print("a", "b", "c", sep = "|")
if __name__ == '__main__':
string_as_list()
basic_string()
numeric_oct_hexadecimal_unicode_escape_sequence()
print_evaluate_string_with_special_character()
string_method_split_join()
string_convert_to_numbers()
strip_string()
string_module_constants()
string_searching()
string_replace()
methods_and_constants()
convert_from_object_to_string()
string_format()
control_print()