blocks|key|2283932|text|重复值与随机值一致。如果不能重复值，则可以使用可能的值创建一个数组，并从该数组中随机删除一个数字，直到它为空，但这将比真正的随机数更不随机。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2283933|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Repeating values is consistent with random. If you can't repeat values, you can create an array with the possible values, and randomly remove a number from this array until it is empty, but this will be less random than a true random number.

blocks|key|2283935|text|希望，这将是有帮助的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2283936|int+r+=+arc4random()%2530%2B30;|code-block|syntax|javascript|2283937|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Hope, it will be helpful:

<pre><code>int r = arc4random()%30+30;
</code></pre>

blocks|key|3336576|text|使用arc4random()，它将提供一个很好的随机数，并且不需要种子。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3336577|rand()将在应用程序每次运行时生成相同的序列，除非您为其设定一个唯一的值。|3336578|那么这就是一个缩小范围的问题。一个简单的解决方案是对范围进行mod，然后添加范围的低端。(这将导致应该可以接受的小偏差。)|3336579|示例：|3336580|int+rangeLow+=+31;
int+rangeHigh+=+60;
int+randomNumber+=+arc4random()+%25+(rangeHigh-rangeLow%2B1)+%2B+rangeLow;|code-block|syntax|javascript|3336581|如果您希望范围内的每个数字只出现一次，那么@pawan.mangal提供了一个很好的解决方案的链接。|3336582|entityMap^0|2|C|0|0|6|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|10|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|11|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|12|8|@]|D|@]|E|$O|P]]|$1|Q|3|R|5|6|7|13|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|T|$]]

Use <code>arc4random()</code>, it will provide a good random number and does not require seeding.

<code>rand()</code> will produce the same sequence each time the app is run unless you seed it with a unique value.

Then it is a matter or reducing the range. A simple solution is to mod to the range and add the low end of the range. (This will cause a small bias that should be acceptable.)

Example:

<pre><code>int rangeLow = 31;
int rangeHigh = 60;
int randomNumber = arc4random() % (rangeHigh-rangeLow+1) + rangeLow;
</code></pre>

If what you want each number in the range to occur only once then @pawan.mangal has a link to a good solution.

blocks|key|373870|text|您可以使用arc4random()代替rand()|type|unstyled|depth|inlineStyleRanges|entityRanges|data|373871|要从arc4random()获得从0到x-1的整数值，您可以这样做：|373872|int+value+=+arc4random()+%25+x;|code-block|syntax|javascript|373873|要获得1到x范围内的整数，只需添加1：|373874|int+value+=+(arc4random()+%25+x)+%2B+1;|373875|最后，如果您需要生成浮点数，请在您的项目中定义：|373876|#define+ARC4RANDOM_MAX++++++0x100000000'|373877|然后，可以使用arc4random()获得一个浮点值(精度是使用rand()的两倍)，介于0和100之间，如下所示：|373878|double+val+=+floorf(((double)arc4random()+/+ARC4RANDOM_MAX)+*+100.0f);|373879|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|T|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

Instead of rand() you can use arc4random() 

To get an integer value from arc4random() that goes from 0 to x-1, you would do this:

<pre><code>int value = arc4random() % x;
</code></pre>

To get an integer in the range 1 to x, just add 1:

<pre><code>int value = (arc4random() % x) + 1;
</code></pre>

Finally, if you need to generate a floating point number, define this in your project:

<pre><code>#define ARC4RANDOM_MAX 0x100000000'
</code></pre>

Then, you can use arc4random() to get a floating point value (at double the precision of using rand()), between 0 and 100, like so:

<pre><code>double val = floorf(((double)arc4random() / ARC4RANDOM_MAX) * 100.0f);
</code></pre>

blocks|key|3336605|text|我想我可以添加一个我在许多项目中使用的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3336606|-+(NSInteger)randomValueBetween:(NSInteger)min+and:(NSInteger)max+{
++++return+(NSInteger)(min+%2B+arc4random_uniform(max+%2B+1);
}|code-block|syntax|javascript|3336607|如果我最终在许多文件中使用它，我通常会将宏声明为|3336608|#define+RAND_FROM_TO(min,max)+(min+%2B+arc4random_uniform(max+%2B+1))|3336609|例如。|3336610|NSInteger+myInteger+=+RAND_FROM_TO(31,60)+//+31,+32,...,+59,+60|3336611|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Thought I could add a method I use in many projects.

<pre><code>- (NSInteger)randomValueBetween:(NSInteger)min and:(NSInteger)max {
 return (NSInteger)(min + arc4random_uniform(max + 1);
}
</code></pre>

If I end up using it in many files I usually declare a macro as

<pre><code>#define RAND_FROM_TO(min,max) (min + arc4random_uniform(max + 1))
</code></pre>

E.g.

<pre><code>NSInteger myInteger = RAND_FROM_TO(31,60) // 31, 32,..., 59, 60
</code></pre>

blocks|key|5448671|text|下面的方法将在你的问题中提到的low和high.as范围内生成一个唯一随机数数组，你需要31到60之间的随机数，所以数组中将有最多29个唯一数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5448672|+-(void)generateRandomUniqueNumberInRange+:(int)rangeLow+:(int)rangeHigh{
++++++++NSMutableArray+*unqArray=[[NSMutableArray+alloc]+init];
++++++++int+randNum+=+arc4random()+%25+(rangeHigh-rangeLow%2B1)+%2B+rangeLow;
++++++++int+counter=0;
++++++++while+(counter<rangeHigh-rangeLow)+{
++++++++++++if+(![unqArray+containsObject:[NSNumber+numberWithInt:randNum]])+{
++++++++++++++++[unqArray+addObject:[NSNumber+numberWithInt:randNum]];
++++++++++++++++counter%2B%2B;
++++++++++++}else{
++++++++++++++++randNum+=+arc4random()+%25+(rangeHigh-rangeLow%2B1)+%2B+rangeLow;
++++++++++++}

++++++++}
++++++++NSLog(@"UNIQUE+ARRAY+%25@",unqArray);

++++}|code-block|syntax|javascript|5448673|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

the follwing method will generate an Array of unique random numbers in range low and high.as you mentioned in your question,you need random number between 31 to 60,so there will be maximum 29 unique numbers in the array.

<pre><code> -(void)generateRandomUniqueNumberInRange :(int)rangeLow :(int)rangeHigh{
 NSMutableArray *unqArray=[[NSMutableArray alloc] init];
 int randNum = arc4random() % (rangeHigh-rangeLow+1) + rangeLow;
 int counter=0;
 while (counter&lt;rangeHigh-rangeLow) {
 if (![unqArray containsObject:[NSNumber numberWithInt:randNum]]) {
 [unqArray addObject:[NSNumber numberWithInt:randNum]];
 counter++;
 }else{
 randNum = arc4random() % (rangeHigh-rangeLow+1) + rangeLow;
 }

 }
 NSLog(@"UNIQUE ARRAY %@",unqArray);

 }
</code></pre>

I want to generate a random number between 31 to 60.

So i have used rand() but i think it will give some time same value.But i need ebvery time it should give me new value.

How can i do this?

Generating unique random number in objective c?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我想生成一个介于31到60之间的随机数。所以我使用了rand()，但我认为它会给我一些时间，我需要同样的value.But，每一次它都应该给我新的值。我该怎么做呢？

问在目标c中生成唯一的随机数？
EN

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问在目标c中生成唯一的随机数？EN