我主要是Java头,我想要一种方法来生成0到74之间的伪随机数。在Java中我会使用方法:
Random.nextInt(74)
我对关于种子或真正随机性的讨论不感兴趣,只是讨论如何在 Objective-C 中完成相同的任务。我搜索了谷歌,似乎有很多不同且相互矛盾的信息。
最佳答案
您应该使用 arc4random_uniform()
函数。它使用优于 rand
的算法。你甚至不需要设置种子。
#include <stdlib.h>
// ...
// ...
int r = arc4random_uniform(74);
arc4random
手册页:
NAME arc4random, arc4random_stir, arc4random_addrandom -- arc4 random number generator LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <stdlib.h> u_int32_t arc4random(void); void arc4random_stir(void); void arc4random_addrandom(unsigned char *dat, int datlen); DESCRIPTION The arc4random() function uses the key stream generator employed by the arc4 cipher, which uses 8*8 8 bit S-Boxes. The S-Boxes can be in about (2**1700) states. The arc4random() function returns pseudo- random numbers in the range of 0 to (2**32)-1, and therefore has twice the range of rand(3) and random(3). The arc4random_stir() function reads data from /dev/urandom and uses it to permute the S-Boxes via arc4random_addrandom(). There is no need to call arc4random_stir() before using arc4random(), since arc4random() automatically initializes itself. EXAMPLES The following produces a drop-in replacement for the traditional rand() and random() functions using arc4random(): #define foo4random() (arc4random() % ((unsigned)RAND_MAX + 1))
https://stackoverflow.com/questions/160890/