Split string using loop to specific length sub-units

Question

I need to split a string into specific lengths, e.g. if user specifies it to units of max length 4, then the loop should run on the original input "0123456789asdf" to get "0123", "4567", "89as", "df".

I can't really figure out the best way to do this - and I need it to be in a loop as further processing needs to be done on each subunit of the strong. TIA.

edit: I do not know how long the original string is, and I only know the size of the chunk it needs to become. Also, I need chunks of the string of the specified length, and the last chunk containing the remainder of the string (if it is less than the specified length).

Answer 1

string str("0123456789asdf");

for (unsigned i = 0; i < str.length(); i += 4) {
    cout << str.substr(i, 4) << endl;
}