Which is the preferred way to concatenate a string in Python?

Question

Since Python\'s string can\'t be changed, I was wondering how to concatenate a string more efficiently?

I can write like it:

s += string         


        

Answer 1

You can do in different ways.

str1 = "Hello"
str2 = "World"
str_list = ['Hello', 'World']
str_dict = {'str1': 'Hello', 'str2': 'World'}

# Concatenating With the + Operator
print(str1 + ' ' + str2)  # Hello World

# String Formatting with the % Operator
print("%s %s" % (str1, str2))  # Hello World

# String Formatting with the { } Operators with str.format()
print("{}{}".format(str1, str2))  # Hello World
print("{0}{1}".format(str1, str2))  # Hello World
print("{str1} {str2}".format(str1=str_dict['str1'], str2=str_dict['str2']))  # Hello World
print("{str1} {str2}".format(**str_dict))  # Hello World

# Going From a List to a String in Python With .join()
print(' '.join(str_list))  # Hello World

# Python f'strings --> 3.6 onwards
print(f"{str1} {str2}")  # Hello World

I created this little summary through following articles.

• Python 3's f-Strings: An Improved String Formatting Syntax (Guide) (Speed test also included)
• Formatted string literals
• String Concatenation and Formatting
• Splitting, Concatenating, and Joining Strings in Python