I assume you are running this under Java 9? You are not altering the SIZED property of the stream, so there is no need to execute either map or peek at all. In other words all you care is about count as the final result, but in the meanwhile you do not alter the initial … Read more
Portably, you can get the next character in the input stream with getchar() and then push it back with ungetc(), which results in a state as if the character wasn’t removed from the stream. The ungetc function pushes the character specified by c (converted to an unsigned char) back onto the input stream pointed to … Read more
fgetc+ungetc. Maybe something like this: int fpeek(FILE *stream) { int c; c = fgetc(stream); ungetc(c, stream); return c; }
For sake of completeness, the more-itertools package (which should probably be part of any Python programmer’s toolbox) includes a peekable wrapper that implements this behavior. As the code example in the documentation shows: >>> p = peekable([‘a’, ‘b’]) >>> p.peek() ‘a’ >>> next(p) ‘a’ However, it’s often possible to rewrite code that would use this … Read more
The important thing you have to understand is that streams are driven by the terminal operation. The terminal operation determines whether all elements have to be processed or any at all. So collect is an operation that processes each item, whereas findAny may stop processing items once it encountered a matching element. And count() may … Read more