7 Efficient Ways to Concatenate Strings in Python

In Python, there are multiple ways to concatenate strings; this guide provides a comprehensive summary for future reference.

Plus (+) Concatenation

Use the + operator to join strings.

a, b = 'hello', ' world'
print(a + b)  # 'hello world'

Comma Concatenation (print only)

Using a comma separates values in print, but assigning with a comma creates a tuple.

a, b = 'hello', ' world'
print(a, b)  # hello  world

# Assignment creates a tuple
(a, b)  # ('hello', ' world')

Direct Literal Concatenation

Place string literals next to each other; whitespace inside the literals is preserved.

print('hello' ' world')
print('hello''world')

Percent (%) Formatting

Before Python 2.6, % was the primary string‑formatting operator and can also be used for concatenation.

print('%s %s' % ('hello', 'world'))

format() Method

The format method, introduced in Python 2.6, replaces % for formatting and can concatenate strings.

print('{}{}'.format('hello', ' world'))

join() Method

The built‑in join method concatenates an iterable of strings with a separator.

print('-'.join(['aa', 'bb', 'cc']))  # aa-bb-cc

f‑string

Introduced in Python 3.6, f‑strings provide a concise way to embed expressions inside string literals, serving as an evolution of % and format.

aa, bb = 'hello', 'world'
print(f'{aa} {bb}')  # hello world

Multiplication (*) Operator

The * operator repeats a string a given number of times.

aa = 'hello '
print(aa * 3)  # hello hello hello

Conclusion

When concatenating a small number of strings

Prefer the + operator. If performance is critical and you are using Python 3.6+, f‑strings are recommended for better readability.

a = f'姓名：{name} 年龄：{age} 性别：{gender}'
b = '姓名：' + name + '年龄：' + age + '性别：' + gender

When concatenating many strings

Use join or f‑strings, depending on your Python version and readability requirements.

Reference

You may not know the Python string concatenation secrets:

https://juejin.im/post/5b350624f265da5954426713