How to append a string in Python?

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In this tutorial, we will see different ways to append a string in Python. The most efficient methods are using the += operator , join() function, and f-strings.

We know that strings are immutable in Python, which means we cannot change the string variable’s value once it’s declared and assigned. However, we can always return a new string.

Append to a String in Python

We will take a look at 3 different ways to append a string in Python.

1. Using += operator
2. Using string.join() method
3. Using Python f-strings

Method 1: Using += operator to append a string

The += (plus equal) operator is similar to any other language that concatenates two strings and returns a new string in Python without changing the original string.

Example: Append to a string using += operator

<span># Python program to append to a string using += operator </span>
<span>first_name</span><span>=</span><span>"Bing"</span>
<span>last_name</span><span>=</span><span>" Chandler"</span>
<span># printing first name </span><span>print</span><span>(</span><span>"The first name is: "</span> <span>+</span> <span>str</span><span>(</span><span>first_name</span><span>))</span>
<span># printing last name </span><span>print</span><span>(</span><span>"The last name is: "</span> <span>+</span> <span>str</span><span>(</span><span>last_name</span><span>))</span>
<span># Using += operator adding one string to another </span><span>first_name</span> <span>+=</span> <span>last_name</span>
<span># print concatenated string </span><span>print</span><span>(</span><span>"The concatenated string is: "</span> <span>+</span> <span>first_name</span><span>)</span>
<span># Python program to append to a string using += operator </span>
<span>first_name</span><span>=</span><span>"Bing"</span>
<span>last_name</span><span>=</span><span>" Chandler"</span>

<span># printing first name </span><span>print</span><span>(</span><span>"The first name is: "</span> <span>+</span> <span>str</span><span>(</span><span>first_name</span><span>))</span>

<span># printing last name </span><span>print</span><span>(</span><span>"The last name is: "</span> <span>+</span> <span>str</span><span>(</span><span>last_name</span><span>))</span>

<span># Using += operator adding one string to another </span><span>first_name</span> <span>+=</span> <span>last_name</span>

<span># print concatenated string </span><span>print</span><span>(</span><span>"The concatenated string is: "</span> <span>+</span> <span>first_name</span><span>)</span>
# Python program to append to a string using += operator 
first_name="Bing"
last_name=" Chandler"

# printing first name print("The first name is: " + str(first_name))

# printing last name print("The last name is: " + str(last_name))

# Using += operator adding one string to another first_name += last_name

# print concatenated string print("The concatenated string is: " + first_name)

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Output

<span>The</span> <span>first</span> <span>name</span> <span>is</span><span>:</span> <span>Bing</span>
<span>The</span> <span>last</span> <span>name</span> <span>is</span><span>:</span> <span>Chandler</span>
<span>The</span> <span>concatenated</span> <span>string</span> <span>is</span><span>:</span> <span>Bing</span> <span>Chandler</span>
<span>The</span> <span>first</span> <span>name</span> <span>is</span><span>:</span> <span>Bing</span>
<span>The</span> <span>last</span> <span>name</span> <span>is</span><span>:</span> <span>Chandler</span>
<span>The</span> <span>concatenated</span> <span>string</span> <span>is</span><span>:</span> <span>Bing</span> <span>Chandler</span>
The first name is: Bing
The last name is: Chandler
The concatenated string is: Bing Chandler

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Method 2: Using join() function to append a string

Another way to append strings in Python is using the join() method. It has an advantage over the += operator as it can append multiple strings or a list of strings.

Example: Append to a string using the join() function

In this example, we pass a list of strings to the join() function, which concatenates them together and returns to the output string.

<span># Python program to append a string using join() function </span>
<span>first_name</span><span>=</span><span>"Bing"</span>
<span>last_name</span><span>=</span><span>" Chandler"</span>
<span># printing first name </span><span>print</span><span>(</span><span>"The first name is: "</span> <span>+</span> <span>str</span><span>(</span><span>first_name</span><span>))</span>
<span># printing last name </span><span>print</span><span>(</span><span>"The last name is: "</span> <span>+</span> <span>str</span><span>(</span><span>last_name</span><span>))</span>
<span># Using join() method to append a string </span><span>result</span><span>=</span> <span>""</span><span>.</span><span>join</span><span>([</span><span>first_name</span><span>,</span><span>last_name</span><span>])</span>
<span># print concatenated string </span><span>print</span><span>(</span><span>"The concatenated string is: "</span> <span>+</span> <span>result</span><span>)</span>
<span># Python program to append a string using join() function </span>
<span>first_name</span><span>=</span><span>"Bing"</span>
<span>last_name</span><span>=</span><span>" Chandler"</span>

<span># printing first name </span><span>print</span><span>(</span><span>"The first name is: "</span> <span>+</span> <span>str</span><span>(</span><span>first_name</span><span>))</span>

<span># printing last name </span><span>print</span><span>(</span><span>"The last name is: "</span> <span>+</span> <span>str</span><span>(</span><span>last_name</span><span>))</span>

<span># Using join() method to append a string </span><span>result</span><span>=</span> <span>""</span><span>.</span><span>join</span><span>([</span><span>first_name</span><span>,</span><span>last_name</span><span>])</span>

<span># print concatenated string </span><span>print</span><span>(</span><span>"The concatenated string is: "</span> <span>+</span> <span>result</span><span>)</span>
# Python program to append a string using join() function 
first_name="Bing"
last_name=" Chandler"

# printing first name print("The first name is: " + str(first_name))

# printing last name print("The last name is: " + str(last_name))

# Using join() method to append a string result= "".join([first_name,last_name])

# print concatenated string print("The concatenated string is: " + result)

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Output

<span>The</span> <span>first</span> <span>name</span> <span>is</span><span>:</span> <span>Bing</span>
<span>The</span> <span>last</span> <span>name</span> <span>is</span><span>:</span> <span>Chandler</span>
<span>The</span> <span>concatenated</span> <span>string</span> <span>is</span><span>:</span> <span>Bing</span> <span>Chandler</span>
<span>The</span> <span>first</span> <span>name</span> <span>is</span><span>:</span> <span>Bing</span>
<span>The</span> <span>last</span> <span>name</span> <span>is</span><span>:</span> <span>Chandler</span>
<span>The</span> <span>concatenated</span> <span>string</span> <span>is</span><span>:</span> <span>Bing</span> <span>Chandler</span>
The first name is: Bing
The last name is: Chandler
The concatenated string is: Bing Chandler

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Method 3: Using f-strings to append a string

If you use Python 3.6 and above version, you can leverage f-strings in Python to append a string.

F-strings provide a way to embed expressions inside string literals , using a minimal syntax. F-strings are prefixed with “f” which contains expression inside braces. These expressions are replaced with their values.

Example: Append to a string using the f-string

<span># Python program to append a string using f-string </span>
<span>first_name</span><span>=</span><span>"Bing"</span>
<span>last_name</span><span>=</span><span>" Chandler"</span>
<span># printing first name </span><span>print</span><span>(</span><span>"The first name is: "</span> <span>+</span> <span>str</span><span>(</span><span>first_name</span><span>))</span>
<span># printing last name </span><span>print</span><span>(</span><span>"The last name is: "</span> <span>+</span> <span>str</span><span>(</span><span>last_name</span><span>))</span>
<span># Using f-string to append a string </span><span>result</span><span>=</span> <span>f</span><span>"</span><span>{</span><span>first_name</span><span>}{</span><span>last_name</span><span>}</span><span>"</span>
<span># print concatenated string </span><span>print</span><span>(</span><span>"The concatenated string is: "</span> <span>+</span> <span>result</span><span>)</span>
<span># Python program to append a string using f-string </span>
<span>first_name</span><span>=</span><span>"Bing"</span>
<span>last_name</span><span>=</span><span>" Chandler"</span>

<span># printing first name </span><span>print</span><span>(</span><span>"The first name is: "</span> <span>+</span> <span>str</span><span>(</span><span>first_name</span><span>))</span>

<span># printing last name </span><span>print</span><span>(</span><span>"The last name is: "</span> <span>+</span> <span>str</span><span>(</span><span>last_name</span><span>))</span>

<span># Using f-string to append a string </span><span>result</span><span>=</span> <span>f</span><span>"</span><span>{</span><span>first_name</span><span>}{</span><span>last_name</span><span>}</span><span>"</span>

<span># print concatenated string </span><span>print</span><span>(</span><span>"The concatenated string is: "</span> <span>+</span> <span>result</span><span>)</span>
# Python program to append a string using f-string 
first_name="Bing"
last_name=" Chandler"

# printing first name print("The first name is: " + str(first_name))

# printing last name print("The last name is: " + str(last_name))

# Using f-string to append a string result= f"{first_name}{last_name}"

# print concatenated string print("The concatenated string is: " + result)

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Output

<span>The</span> <span>first</span> <span>name</span> <span>is</span><span>:</span> <span>Bing</span>
<span>The</span> <span>last</span> <span>name</span> <span>is</span><span>:</span> <span>Chandler</span>
<span>The</span> <span>concatenated</span> <span>string</span> <span>is</span><span>:</span> <span>Bing</span> <span>Chandler</span>
<span>The</span> <span>first</span> <span>name</span> <span>is</span><span>:</span> <span>Bing</span>
<span>The</span> <span>last</span> <span>name</span> <span>is</span><span>:</span> <span>Chandler</span>
<span>The</span> <span>concatenated</span> <span>string</span> <span>is</span><span>:</span> <span>Bing</span> <span>Chandler</span>
The first name is: Bing
The last name is: Chandler
The concatenated string is: Bing Chandler

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原文链接：How to append a string in Python?