How can I create a random number within a range? I tried following code but it didn't accomplish my task.
int fromNumber = 10;
int toNumber = 30;
int randomNumber = (arc4random()%(toNumber-fromNumber))+fromNumber;
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BergQuester
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Shairjeel ahmed
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1What did it do? What did you not like about the result? – rob mayoff Aug 15 '13 at 22:26
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2What made you use 10 and 30 when you wanted a number between 4 and 10? – WendiKidd Aug 15 '13 at 22:30
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SORRY i just made some mistake while posting but in program it is 4 and 10... – Shairjeel ahmed Aug 15 '13 at 22:40
2 Answers
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There are seven numbers between 4 and 10 inclusive. arc4random_uniform() is recommended over arc4random() for this purpose.
int randomNumber = arc4random_uniform(7) + 4
The more general case is arc4random_uniform(upper_bound - lower_bound + 1) + lower_bound.
Jeffery Thomas
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can any body provide me some useful tutorial to lean arc4random and arc4random_uniform – Shairjeel ahmed Aug 15 '13 at 22:43
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1@user1275440 you should search the web yourself, it is just a function! – moonwave99 Aug 15 '13 at 22:45
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Update
I was unaware of arc4random_uniform() before so i recommend https://stackoverflow.com/a/18262992/2611613 as the answer. The answer i linked below still has a good explanation of a general approach to this problem without worrying about languages.
Your answer should work. Without knowing what is wrong with what you have i can only guess at the problem.
Currently you have
int randomNumber = ( arc4random() % ( toNumber - fromNumber ) ) + fromNumber;
This produces a range [from-to) exclusive where you will never get the value toNumber. If you want your random number be able to get include toNumber
int randomNumber = ( arc4random() % ( toNumber - fromNumber + 1 ) ) + fromNumber;
With this you would get a range [from-to] inclusive.
You might look at https://stackoverflow.com/a/363732/2611613 for a really good explanation of how this works.
