separate digits of a long number in c++ -

i have example long number 12345678901 , want separately each digit use it. tried hard didn't make far? ideas?

but have problem in of them when try number of 11 digits , more (that want) program stops working i'm running program in visual studio in other case-smaller numbers--is fine.. connection fact number long?

this give digits in variable b.

long = 12345678901; while(a > 0) {    long b = % 10;    /= 10; }