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Iterator end check fails after incrementing inside a `for` loop


Iterator end check fails after incrementing inside a `for` loop

By : Klaus
Date : November 21 2020, 09:01 AM
wish of those help You are checking for it != vec.end() but with it++ happening twice you are skipping twice on each check. In other words you are running past the end of the vector without spotting it.
If you add one more element to your vector then the loop will hit the end and stop as you will no longer skip the end point (obviously this is not a "proper" fix, it just demonstrates the problem).
code :


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python arbitrarily incrementing an iterator inside a loop

python arbitrarily incrementing an iterator inside a loop


By : user1472637
Date : March 29 2020, 07:55 AM
will be helpful for those in need There is a fantastic package in Python called itertools.
But before I get into that, it'd serve well to explain how the iteration protocol is implemented in Python. When you want to provide iteration over your container, you specify the __iter__() class method that provides an iterator type. "Understanding Python's 'for' statement" is a nice article covering how the for-in statement actually works in Python and provides a nice overview on how the iterator types work.
code :
>>> sequence = [1, 2, 3, 4, 5]
>>> iterator = sequence.__iter__()
>>> iterator.next()
1
>>> iterator.next()
2
>>> for number in iterator:
    print number 
3
4
5
def consume(iterator, n):
    '''Advance the iterator n-steps ahead. If n is none, consume entirely.'''
    collections.deque(itertools.islice(iterator, n), maxlen=0)
>>> import itertools, collections
>>> def consume(iterator, n):
    collections.deque(itertools.islice(iterator, n))
>>> iterator = range(1, 16).__iter__()
>>> for number in iterator:
    if (number == 5):
        # Disregard 6, 7, 8, 9 (5 doesn't get printed just as well)
        consume(iterator, 4)
    else:
        print number

1
2
3
4
10
11
12
13
14
15
Forking inside loop preventing iterator from incrementing with Parallel::Prefork

Forking inside loop preventing iterator from incrementing with Parallel::Prefork


By : Zaym Likma
Date : March 29 2020, 07:55 AM
With these it helps Contrary to the documentation, Parallel::Prefork is very different than Parallel::ForkManager. It's designed to be used by something like a web server, which loads a config once then just spawns identical children until it's shut down by a signal.
As such, start keeps creating children as needed, and doesn't return until a signal meant to terminate the whole process is caught.
code :
use strict;
use warnings;
use v5.10;

use List::MoreUtils   qw( natatime );
use Parallel::Prefork qw( );
use POSIX             qw( ceil );

my $forks = 2;

my @numbers       = (1..10);
my $chunk_size    = ceil(@numbers / $forks);
my $game_iterator = natatime($chunk_size, @numbers);

my @numbers_chunk;

my $fm = Parallel::Prefork->new({
   max_workers => $forks,
   trap_signals => { TERM => 'TERM' },
   before_fork => sub {
      @numbers_chunk = $game_iterator->()
         or kill(TERM => $$);
   },
});

$fm->start(sub {
   say $numbers_chunk[0];
});

$fm->wait_all_children();
Incrementing iterator and passing the argument in a recursion loop

Incrementing iterator and passing the argument in a recursion loop


By : Banaba Coron
Date : March 29 2020, 07:55 AM
I wish this helpful for you *vec.end() is incorrect. What is the purpose of the return value ? You should use reference to avoid to copy vector each time. Add some constness.
Fixed version:
code :
void pvec(std::vector<int>::const_iterator po, const std::vector<int>& vec)
{
    if(po != vec.end()) {
        std::cout << *po++ << std::endl;
        pvec(po, vec);
    }
}
C++ infinite loop when assigning and post incrementing the loop iterator (gcc bug?)

C++ infinite loop when assigning and post incrementing the loop iterator (gcc bug?)


By : NonEntity
Date : March 29 2020, 07:55 AM
I wish this help you The behaviour of i = i++ is undefined (simultaneous read write in an unsequenced step - and that is in the standard). Never use it.
Note that i = ++i is defined from C++11.
JavaScript loop performance - Why is to decrement the iterator toward 0 faster than incrementing

JavaScript loop performance - Why is to decrement the iterator toward 0 faster than incrementing


By : user3912508
Date : March 29 2020, 07:55 AM
Any of those help I'm not sure about Javascript, and under modern compilers it probably doesn't matter, but in the "olden days" this code:
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