我可以在Swift中直接比较数字和字符串格式吗？ [英] Can I compare number with string format directly in Swift?
问题描述
我发现我可以在Swift中直接比较String格式的两个数字。
I found I can compare two numbers in String format directly in Swift.
最初，我试图将String格式的数字转换为double或Int，然后做比较。当我偶然发现我可以直接比较它们时，我已经在操场上进行了一些测试。看起来结果都是正确的，即使数字是空字符串或（Double）与（Int）。
（例外）：使用String格式的负数的测试用例将
Initially, I was trying to cast my String format number to double or Int, and then do the comparison. When I accidentally found I can compare them directly, I have done some tests in my playground. It seems the result are all correct, even with the numbers are empty string or "(Double)" vs "(Int)".
(Exceptions): The test cases with negative numbers in the String format will fail the comparing.
有人知道这是Swift String中的默认行为吗？我不确定是否可以在程序中使用它。
Does anyone know if this is a default behavior in Swift String? I am not sure if I can utilize this in my program.
示例：
var numStrs1 = ["15", "12.2", "15", ""]
var numStrs2 = ["13", "12", "", "23.0"]
func compareNumStr(numStr1:String, numStr2:String) -> Bool {
return numStr1 > numStr2
}
for var i = 0; i < numStrs1.count; ++i{
compareNumStr(numStrs1[i], numStrs2[i])
}
推荐答案
字符串比较的默认实现所依赖的是 Unicode归类算法来源： http://oleb.net/blog/2014/07/swift-strings/
What the default implementation of string comparisons rely on is the Unicode collation algorithm source: http://oleb.net/blog/2014/07/swift-strings/
您现在进行的比较不是典型的 Int / Double 比较，而是它如何转换为unicode。根据您希望使用这些信息的方式，它可能并不适合所有情况。就像发现负数一样，应该使用 .toInt 方法获取所需的数字，然后比较整数而不是比较字符串。
The comparison you're making right now is not a canonical Int/Double comparison, but rather how it translates to unicode. Depending on how you wish to use the information, it may not be suitable for all scenarios. Like you found out with negative numbers, you should use to .toInt method to get the number you want, and compare the integers instead of comparing the strings.
这篇关于我可以在Swift中直接比较数字和字符串格式吗？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
