C equivalent to fstream’s peek
fgetc+ungetc. Maybe something like this: int fpeek(FILE *stream) { int c; c = fgetc(stream); ungetc(c, stream); return c; }
peek
java BlockingQueue does not have a blocking peek?
You could use a LinkedBlockingDeque and physically remove the item from the queue (using takeLast()) but replace it again at the end of the queue if processing fails using putLast(E e). Meanwhile your “producers” would add elements to the front of the queue using putFirst(E e). You could always encapsulate this behaviour within your own … Read more
Reading specific number of bytes from a buffered reader in golang
Note that the bufio.Read method calls the underlying io.Read at most once, meaning that it can return n < len(p), without reaching EOF. If you want to read exactly len(p) bytes or fail with an error, you can use io.ReadFull like this: n, err := io.ReadFull(reader, p) This works even if the reader is buffered.
Can I get an item from a PriorityQueue without removing it yet?
If a is a PriorityQueue object, You can use a.queue[0] to get the next item: from queue import PriorityQueue a = PriorityQueue() a.put((10, “a”)) a.put((4, “b”)) a.put((3,”c”)) print(a.queue[0]) print(a.queue) print(a.get()) print(a.queue) print(a.get()) print(a.queue) output is : (3, ‘c’) [(3, ‘c’), (10, ‘a’), (4, ‘b’)] (3, ‘c’) [(4, ‘b’), (10, ‘a’)] (4, ‘b’) [(10, ‘a’)] but … Read more
Peeking in a heap in python
Yes, you can make this assumption, because it is stated in the documentation: Heaps are arrays for which heap[k] <= heap[2*k+1] and heap[k] <= heap[2*k+2] for all k, counting elements from zero. For the sake of comparison, non-existing elements are considered to be infinite. The interesting property of a heap is that heap[0] is always … Read more
Stream.peek() method in Java 8 vs Java 9
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
How to look ahead one element (peek) in a Python generator?
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
In Java streams is peek really only for debugging?
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