iOS - int (unsigned int) 最大值是 2147483647，unsigned int 不起作用？
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iOS - int (unsigned int) maximum value is 2147483647, unsigned int doesn't work?
提问by Jonathan Gurebo
the maximum value for an 32-Bit integer is: 2^31-1 = 2147483647. but just with negative and positive number. because the half of the number is negative. so the real maximum value is 2^32-1 = 4294967295. but in this case we just use positive numbers.
32 位整数的最大值为：2^31-1 = 2147483647。但只有负数和正数。因为数字的一半是负数。所以真正的最大值是 2^32-1 = 4294967295。但在这种情况下，我们只使用正数。
ok, a normal int is both negative and positive number. i want to use just positive number because i want the maximum value to be: 4294967295. i'm going to use "unsigned int" instead of "int"
好的，正常的 int 是负数和正数。我只想使用正数，因为我希望最大值为：4294967295。我将使用“unsigned int”而不是“int”
but this will not work! the maximum value is still 2147483647.
但这行不通！最大值仍然是 2147483647。
here is the code for a simple random number generator:
这是一个简单的随机数生成器的代码：
-(Action for my button) {
unsigned int minNumber;
unsigned int maxNumber;
unsigned int ranNumber;
minNumber=[self.textFieldFrom.text intValue]; //getting numbers from my textfields
maxNumber=[self.textFieldTo.text intValue]; //Should i use unsigned intValue?
ranNumber=rand()%(maxNumber-minNumber+1)+minNumber;
NSString *str = [NSString stringWithFormat:@"%d", ranNumber];
self.label.text = str;
}
and this will view : 2147483647 as a maximum value.
这将查看： 2147483647 作为最大值。
what's wrong? should i use unsigned intValue when i getting numbers from my textFields?
怎么了？当我从文本字段中获取数字时，我应该使用 unsigned intValue 吗？
Jonathan
乔纳森
here you can read about this number. : http://en.wikipedia.org/wiki/2147483647
您可以在此处阅读有关此号码的信息。: http://en.wikipedia.org/wiki/2147483647
回答by Rob
The problem is intValuewhich returns a int(not an unsigned int) and is maxed out at 2,147,483,647. If you need larger than INT32_MAX, then use longvariables and NSStringmethod longLongValueinstead of intValue.
问题是intValue哪个返回 a int（不是 an unsigned int）并且最大值为 2,147,483,647。如果您需要大于INT32_MAX，则使用long变量和NSString方法longLongValue而不是intValue。
Yes, %dis signed, but if you use %uthat will not solve the problem with intValue. Using long longvariables and longlongValuemethod will solve this. For example:
是的，%d已签名，但如果您使用%u它并不能解决intValue. 使用long long变量和longlongValue方法将解决这个问题。例如：
NSString *string = @"2147483650";
unsigned int i = [string intValue];
NSLog(@"i = %u", i); // returns 2147483647
NSUInteger j = [string integerValue];
NSLog(@"j = %u", j); // returns 2147483647
long long k = [string longLongValue];
NSLog(@"k = %lld", k); // returns 2147483650
So, looking at your original code, it might be:
因此，查看您的原始代码，它可能是：
long long minNumber;
long long maxNumber;
long long ranNumber;
minNumber = [self.textFieldFrom.text longLongValue];
maxNumber = [self.textFieldTo.text longLongValue];
ranNumber = arc4random_uniform(maxNumber-minNumber+1) + minNumber;
NSString *str = [NSString stringWithFormat:@"%lld", ranNumber];
self.label.text = str;
回答by Nickolay Olshevsky
%d modifier is parsed as signed integer.
%d 修饰符被解析为有符号整数。
