primesieve_iterator allows to easily iterate over primes both forwards and backwards. More...

#include <stdint.h>
#include <stddef.h>

Include dependency graph for iterator.h:

This graph shows which files directly or indirectly include this file:

Classes
struct	primesieve_iterator
	C prime iterator, please refer to iterator.h for more information. More...

Functions
void	primesieve_init (primesieve_iterator *it)
	Initialize the primesieve iterator before first using it.

void	primesieve_free_iterator (primesieve_iterator *it)
	Free all memory.

void	primesieve_skipto (primesieve_iterator *it, uint64_t start, uint64_t stop_hint)
	Reset the primesieve iterator to start. More...

static uint64_t	primesieve_next_prime (primesieve_iterator *it)
	Get the next prime. More...

static uint64_t	primesieve_prev_prime (primesieve_iterator *it)
	Get the previous prime. More...

Detailed Description

primesieve_iterator allows to easily iterate over primes both forwards and backwards.

Generating the first prime has a complexity of O(r log log r) operations with r = n^0.5, after that any additional prime is generated in amortized O(log n log log n) operations. The memory usage is about PrimePi(n^0.5) * 8 bytes.

The primesieve_iterator.c example shows how to use primesieve_iterator. If any error occurs primesieve_next_prime() and primesieve_prev_prime() return PRIMESIEVE_ERROR. Furthermore primesieve_iterator.is_error is initialized to 0 and set to 1 if any error occurs.

This file is distributed under the BSD License. See the COPYING file in the top level directory.

Function Documentation

◆ primesieve_next_prime()

static uint64_t primesieve_next_prime ( primesieve_iterator * it )

inlinestatic

Get the next prime.

Returns UINT64_MAX if next prime > 2^64.

Examples:: primesieve_iterator.c.

◆ primesieve_prev_prime()

static uint64_t primesieve_prev_prime ( primesieve_iterator * it )

inlinestatic

Get the previous prime.

primesieve_prev_prime(n) returns 0 for n <= 2. Note that primesieve_next_prime() runs up to 2x faster than primesieve_prev_prime(). Hence if the same algorithm can be written using either primesieve_prev_prime() or primesieve_next_prime() it is preferable to use primesieve_next_prime().

Examples:: prev_prime.c.

◆ primesieve_skipto()

void primesieve_skipto	(	primesieve_iterator *	it,
		uint64_t	start,
		uint64_t	stop_hint
	)

Reset the primesieve iterator to start.

Parameters

start	Generate primes > start (or < start).
stop_hint	Stop number optimization hint. E.g. if you want to generate the primes below 1000 use stop_hint = 1000, if you don't know use primesieve_get_max_stop().

Examples:: prev_prime.c, and primesieve_iterator.c.

Classes

Functions

Detailed Description

Function Documentation

◆ primesieve_next_prime()

◆ primesieve_prev_prime()

◆ primesieve_skipto()