How to append one string to another in Python

How to append one string to another in Python

Appending one string to another string in Python; In this tutorial, you will learn how to append one string to another string.

Python String Append

Python string object is immutable. So many time you use + operator to concatenate or join two strings in python programming and created a new string in python.

If you have to append many strings, using + operator will unnecessarily create many temporary strings before we have the final result.

Let’s look at a function to join a string ‘n’ times:

def str_append(s, n):
    output = ''
    i = 0
    while i < n:
        output += s
        i = i + 1
    return output

Notice:- that I am defining this function to showcase the usage of + operator. I will later use timeit module to test the performance. If you simply want to concatenate a string ‘n’ times, you can do it easily using s = 'Hi' * 10.

Another way to join/concatenate string append operation is by creating a python list and appending strings to the python list. Then use python string join() function to join/merge string and list together to get the result string.

def str_append_list_join(s, n):
    l1 = []
    i = 0
    while i < n:
        l1.append(s)
        i += 1
    return ''.join(l1)

Let’s examine these methods to make sure they are working as supposed.

if __name__ == "__main__":
    print('Append using + operator:', str_append('Hi', 10))
    print('Append using list and join():', str_append_list_join('Hi', 10))
    # use below for this case, above methods are created so that we can
    # check performance using timeit module
    print('Append using * operator:', 'Hi' * 10)

Output:

Append using + operator: HiHiHiHiHiHiHiHiHiHi
Append using list and join(): HiHiHiHiHiHiHiHiHiHi
Append using * operator: HiHiHiHiHiHiHiHiHiHi

A simple way to append strings in Python

You need to have both the methods defined in string_append.py file. Let’s use timeit module to check their performance.

$ python3.7 -m timeit --number 1000 --unit usec 'import string_append' 'string_append.str_append("Hello", 1000)' 
1000 loops, best of 5: 174 usec per loop
$ python3.7 -m timeit --number 1000 --unit usec 'import string_append' 'string_append.str_append_list_join("Hello", 1000)'
1000 loops, best of 5: 140 usec per loop

$ python3.7 -m timeit --number 1000 --unit usec 'import string_append' 'string_append.str_append("Hi", 1000)' 
1000 loops, best of 5: 165 usec per loop
$ python3.7 -m timeit --number 1000 --unit usec 'import string_append' 'string_append.str_append_list_join("Hi", 1000)'

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AuthorAdmin

My name is Devendra Dode. I am a full-stack developer, entrepreneur, and owner of Tutsmake.com. I like writing tutorials and tips that can help other developers. I share tutorials of PHP, Python, Javascript, JQuery, Laravel, Livewire, Codeigniter, Node JS, Express JS, Vue JS, Angular JS, React Js, MySQL, MongoDB, REST APIs, Windows, Xampp, Linux, Ubuntu, Amazon AWS, Composer, SEO, WordPress, SSL and Bootstrap from a starting stage. As well as demo example.

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