Re: let vs double-parentheses

[Peng Yu]

> - For another example, when one wants to process arguments as
> arithmetic expressions, one may write something like `let "$@"' using
> let. If one wants to do it with `((...))', one needs to combine it
> with a for loop as `for expr; do ((expr)); done'.
>
> - For a more practical example, when one wants to calculate
> 1+2+3+....+100, one can write `let a=0 a+={1..100}' using let, but
> need to write `a=0; for ((i=1;i<100;i++)); do ((a+=i)); done' using
> `((...))'.

Thanks for the info.

Performance-wise, it seems that "let" may be better in certain cases.
I was not aware of this syntax `a+={1..100000}`. Is there any other
syntax that could have better performance as well?

$ time let a=0 a+={1..100000}

real    0m0.306s
user    0m0.295s
sys     0m0.009s
$ time { a=0; for ((i=1;i<=100000;i++)); do ((a+=i)); done; }

real    0m0.611s
user    0m0.607s
sys     0m0.001s

-- 
Regards,
Peng