Summary of Python string concatenation methods (code)

The content of this article is a summary (code) of Python string splicing methods. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Python generally has the following methods of splicing strings:

① Splice directly through the ( ) operator

s = 'Hello'+' '+'World'+'!'
print(s)

Output results: Hello World!

Using this method to connect strings is inefficient, because when splicing two strings in python, a new string will be generated. To generate a new string, you need to apply for memory again. , when there are many strings to be spliced, it will naturally affect the efficiency.

②Splicing through the str.join() method

strlist=['Hello',' ','World','!']
print(''.join(strlist))

Output result: Hello World!

This method is generally used to convert sets is a string, ''.join() where '' can be a null character or any other character. When it is any other character, the strings in the set will be separated by this character, for example:

strlist=['Hello',' ','World','!']
print(','.join(strlist))

Output result: Hello, ,World,!

③Splicing through str.format() method

s='{} {}!'.format('Hello','World')
print(s)

Output result: Hello World!

When splicing strings in this way, it should be noted that the number of {} in the string must be consistent with the number of format method parameters, otherwise an error will be reported.

④Splicing through the (%) operator

s = '%s %s!' % ('Hello', 'World')
print(s)

Output result: Hello World!

This method is the same as str.format( ) are basically used in the same way.

⑤ Splicing multiple lines through ()

s = (
'Hello'
' '
'World'
'!'
)
print(s)

Output result: Hello World!

When python encounters unclosed parentheses, it will automatically Rows are spliced ​​into one row.

⑥Splicing through the Template object in the string module

from string import Template
s = Template('${s1} ${s2}!') 
print(s.safe_substitute(s1='Hello',s2='World'))

Output result: Hello World!

The implementation of Template is to first initialize one through Template String. These strings contain keys one by one. By calling substitute or safe_subsititute, the key value is matched with the parameters passed in the method, thereby importing the string at the specified location. The advantage of this method is that you don’t need to worry about exceptions caused by inconsistent parameters, such as:

from string import Template
s = Template('${s1} ${s2} ${s3}!') 
print(s.safe_substitute(s1='Hello',s2='World'))

Output result: Hello World ${s3}!

⑦Splicing through F-strings

In python3.6.2 version, PEP 498 proposes a new string formatting mechanism, called "string interpolation" or more commonly known as F-strings, F-strings provides A clear and convenient way to embed python expressions into strings for formatting:

s1='Hello'
s2='World'
print(f'{s1} {s2}!')

Output result: Hello World!

In F-strings we You can also execute the function:

def power(x):
return x*x
x=4
print(f'{x} * {x} = {power(x)}')

Output result: 4 * 4 = 16

And F-strings runs very fast, compared to the two formats %-string and str.format() methods are much faster.

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