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

Using in place string concatenation by '+' is THE WORST method of concatenation in terms of stability and cross implementation as it does not support all values. PEP8 standard discourages this and encourages the use of format(), join() and append() for long term use.

As quoted from the linked "Programming Recommendations" section:

For example, do not rely on CPython's efficient implementation of in-place string concatenation for statements in the form a += b or a = a + b. This optimization is fragile even in CPython (it only works for some types) and isn't present at all in implementations that don't use refcounting. In performance sensitive parts of the library, the ''.join() form should be used instead. This will ensure that concatenation occurs in linear time across various implementations.