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Otu Michael
Otu Michael

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Python3 Programming - Exercise 7 - String operations and function

String operations and function

A string is a sequence of at least zero characters enclosed within (delimiter by) an opened and closed single ( '' ) or double ( "" ) quotation marks. These include any character, even space or numbers. Eg: 'swift Python', "Alan Turing", "Michael Jordan - 23"

String operations

These are operations done on strings objects. These operations are string concatenation and string repetition. We use the addition, +, and multiplication, *, operators, respectively, to concatenate (join) and repeat strings.

Example

Concatenation, in this context, is adding one string to another string.

# String concatenation
first_name = 'Daniel'
last_name  = "Doe"
full_name = first_name + " " + last_name

# we added the first name, space and then the last name to
# produce a full name. The " " is an empty string but
# with space between the delimiters
# output => Daniel Doe
# Without space, we'd have, DanielDoe as the output

# String repetition
# Lets say we want to repeat a particular string for n
# number of times, we do, string * n.
# Lets try to repeat "Hello" three time
h = "Hello"
print(h * 3)
# output=> HelloHelloHello
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String function

These function will help us format the string. There is a lot of these functions on the Python docs.

Calling the function

A function as we would discuss later is a piece of code that does something - performs certain computation. Do my_string.function() to call a string function on a string object.


########### String functions ###########

name = "John"

# change of a name to lower case
print(name.lower())

# change of a name to upper case
print(name.upper())

# capitalize of a name - the first character becomes upper
# and the rest lower
print(name.capitalize())

# return string as a title format
print(name.title())

# remove (strip) 'h' from the name
print(name.strip('h'))

# find the length or size (number of characters) in name
print(len(name))

# split a string by some char
str_split = "hello world"
str_list = str_split.split(' ')  # ['hello', 'world']
print(str_list)

# join
list_str = ['hello', 'world']
new_str = " ".join(list_str)
print(new_str)  # "hello world"

# join with some character, say $
list_str = ['hello', 'world']
new_str = "$".join(list_str)
print(new_str)  # "hello$world"

# There is a whole lot on the Python home page
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Practical

  • Write a program to take input from the user, print the input, separated by a short-dash, -, and the length of the string. Eg: input='Doe', output=Doe - 3
  • Write a program that reads data from the user and converts the data to lower case, upper case, title and capitalize.

Summary

  • String concatenation - add ( join) one string onto another. Eg: name = 'Future' + ' ' + 'Dann'.
  • String repetition - repeat a string for n-times. Eg: print("Green tea" * 2).
  • Do my_string.function_name() to call a string function.

Discussion (1)

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nitinkatkam profile image
Nitin Reddy

Although string concatenation is great for when you have few variables and short string literals, Python has string interpolation to join string variables with string literals. Look at this:

first_name = "Nitin"
last_name = "Reddy"
full_name = f"{first_name} {last_name}"
print(full_name)
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It saves time and reduces complexity when have a more complex string like this:

msg = f"Dear {full_name}, Please note that your payment of {amount} is due on {due_date}. -The Electric Company"
print(msg)
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