How good is startswith?
python
Solution
I'd agree with the others that startswith is more readable, and you should use that. That said, if performance is a big issue for such a special case, benchmark it:
$ python -m timeit -s 'text="foo"' 'text.startswith("a")'
1000000 loops, best of 3: 0.537 usec per loop
$ python -m timeit -s 'text="foo"' 'text[0]=="a"'
1000000 loops, best of 3: 0.22 usec per loop
So `text[0]` is amost 2.5 times as fast - but it's a pretty quick operation; you'd save ~0.3 microseconds per compare depending on the system. Unless you're doing millions of comparisons in a time critical situation though, I'd still go with the more readable startswith.
Problem
Is ``` text.startswith('a') ``` better than ``` text[0]=='a' ``` ? Knowing text is not empty and we are only interested in the first character of it.