Different Random Number Algorithms in Objective-C for iOS Development (arc4random, random, srandom)

Jun 17, 2012#ccplusplus #ios #objective-c #random53

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This article discusses different random number algorithms in Objective-C for iOS development. It explains that Objective-C does not provide direct functions for generating random data, but various random algorithms from C can be used. The article mentions the use of arc4random, random()/rand(), and srandom()/srand() functions, along with their respective parameters and return values. It also notes that the rand series of random numbers use pseudo-random algorithms and suggests using different random seeds for different calls.

Objective-C does not directly provide functions or methods for generating random data. However, we can directly use various random algorithms in C. The following are several common random number algorithms that can be referenced using the stdlib.h header file.

arc4random does not require a random seed and automatically generates a random seed when called. Returns a set of [0, X) int value = arc4random() % x; Returns a set of [1, X] int value = (arc4random() % x) + 1;

random()/rand() does not use a seed and returns any number within the long/int range. Note that random returns long and rand returns int.

srandom(unsigned)/srand(unsigned) uses a random seed and returns any number between the parameter and RAND_MAX. Note that srandom can use unsigned long as a parameter.

It is important to note that the rand series of random numbers use pseudo-random algorithms, so it is recommended to use different random seeds when calling them. For example: srand(time(NULL))