int i;
for (i=0; i<10; i++)
{
    if (string.substr(i,1) == something)
    {
        i += some_other_function();
        retry;
    }
    else if (string.substr(i,1) == something_else)
    {
        i += some_other_function2();
        retry;
    }
    // Otherwise, simply execute the "i++" and re-test
}