NSString 到 NSUInteger

发布于 2024-08-30 14:44:23 字数 79 浏览 3 评论 0原文

我在 NSString @"15" 中有一个数字。我想将其转换为 NSUInteger，但我不知道该怎么做......

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七颜 2024-09-06 14:44:23

NSString *str = @"15";
// Extract an integer number, returns 0 if there's no valid number at the start of the string.
NSInteger i = [str integerValue];

如果您确实想要一个 NSUInteger，只需转换它即可，但您可能需要事先测试该值。

NSString *str = @"15";
// Extract an integer number, returns 0 if there's no valid number at the start of the string.
NSInteger i = [str integerValue];

If you really want an NSUInteger, just cast it, but you may want to test the value beforehand.

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瀟灑尐姊 2024-09-06 14:44:23

当前选择的答案对于 NSUInteger 来说不正确。正如 Corey Floyd 指出的对所选答案的评论，如果该值大于 INT_MAX，则该值将不起作用。更好的方法是使用 NSNumber，然后使用 NSNumber 上的方法之一来检索您感兴趣的类型，例如：

NSString *str = @"15"; // Or whatever value you want
NSNumber *number = [NSNumber numberWithLongLong: str.longLongValue];
NSUInteger value = number.unsignedIntegerValue;

The currently chosen answer is incorrect for NSUInteger. As Corey Floyd points out a comment on the selected answer this won't work if the value is larger than INT_MAX. A better way of doing this is to use NSNumber and then using one of the methods on NSNumber to retrieve the type you're interested in, e.g.:

NSString *str = @"15"; // Or whatever value you want
NSNumber *number = [NSNumber numberWithLongLong: str.longLongValue];
NSUInteger value = number.unsignedIntegerValue;

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梦行七里 2024-09-06 14:44:23

所有这些答案在 64 位系统上都是错误的。

NSScanner *scanner = [NSScanner scannerWithString:@"15"];
unsigned long long ull;
if (![scanner scanUnsignedLongLong:&ull]) {
  ull = 0;  // Or handle failure some other way
}
return (NSUInteger)ull;  // This happens to work because NSUInteger is the same as unsigned long long at the moment.

使用 9223372036854775808 进行测试，它不适合有符号的 long long。

All these answers are wrong on a 64-bit system.

NSScanner *scanner = [NSScanner scannerWithString:@"15"];
unsigned long long ull;
if (![scanner scanUnsignedLongLong:&ull]) {
  ull = 0;  // Or handle failure some other way
}
return (NSUInteger)ull;  // This happens to work because NSUInteger is the same as unsigned long long at the moment.

Test with 9223372036854775808, which won't fit in a signed long long.

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