Regular expressions are nice, but I don't think I'd use a library to deal with whitespace. You could easily just use a C function like sscanf() that will ignore whitespace. Something like:
or if you were reading from a file, you could use fscanf() which is the same thing, but it uses a file for its first parameter. In a way, C has functions that use a regular expression, like sscanf, but it's just not as complex as something like Perl style regex's. So I'd suggest looking more into the different string functions C. Anyway, good luck.
const char line = "blah 123, 456, 789";
int i1, i2, i3;
sscanf(line, "%s %d, %d, %d", str, &i1, &i2, &i3);
"anyint3: %d\n", str, i1, i2, i3);