Tip: Read the notes in the "Modulo check confirmation example" very carefully. There is a bit of important information there that occurs nowhere else in the description.

bad practice

Handy and readable.

Perfect example to learn "loop for" inside join method

if he used const that makes him can't erase

I know, but it's one of the most efficient methods

python new test frameworks

This code is more like english

It's bad practice to remove them. It's relying on the tests to include them instead, which leaves these solutions prone to being automatically invalidated in the future if the tests change and their solutions don't compile anymore. The line or two saved by omitting them isn't worth that risk, so you're doing good by keeping them in

why theres no #include
i tried it without the lib but dosnt work for me

Very readable and logical. Oh, this language design...

where did 'const' go?

Oh, yes... I see...

but the return value will be retuned as an integer. it won't convert to a char. that's not what you want the function to do