Randomly pick between 2 defined ints

Question

Is there a method in objective-c that allows you to pseudorandomly decide between two ints? Or is there a quick way to implement this?

For a detailed discussion on Random numbers in objective-c (including why you shouldn't use rand!) see http://stackoverflow.com/questions/160890/generating-random-numbers-in-objective-c. — RB., Apr 21 '11 at 08:55

score 4 · Accepted Answer · answered Apr 21 '11 at 08:54

4

Use the following:

int number = arc4random() % 2;
if(number==0){
  //pick one number
}else{
  //pick other number
}

answered Apr 21 '11 at 08:54

Tovi7

A slight better looking is to use ternary operator. +1 though. – taskinoor Apr 21 '11 at 09:08
That is a uselessly heavy calculation. Why arc4? No simple random that returns float in between 0 and 0,(9) in ObjC? – Apr 25 '11 at 11:38

taskinoor · Answer 2 · 2011-04-21T09:06:51.110

2

randomSelection = arc4random() % 2 ? choice1 : choice2;

edited Apr 21 '11 at 09:06

answered Apr 21 '11 at 08:53

taskinoor

score 0 · Answer 3 · answered Apr 21 '11 at 08:53

0

in C++ that would be result = rand() < 0.5 ? int1 : int2 why can't you build the same command in ObjC?

answered Apr 21 '11 at 08:53

1

This will almost always return int2 unless rand() returns 0. – taskinoor Apr 21 '11 at 08:57
Why? `rand()` returns float. May be it's Linux-specific? Anyway, I assume it is easy enough to figure out what I meant with this code. – Apr 22 '11 at 05:26
In which version of C++ or GCC rand() returns float? – taskinoor Apr 22 '11 at 12:04

3 Answers3