你如何在swift中使用解析字符串？

Question

这里有一个问题，如果我使用解析字符串作为计算器程序的结果，

4.5 * 5.0 = 22.5 

如何在这里使用拆分从结果中删除小数部分？

Answer 1

从结果中使用modf extract decimal part。

Objective-C ：

double integral = 22.5;
double fractional = modf(integral, &integral);
NSLog(@"%f",fractional);

Swift ：

 var integral:Double  = 22.5;
 let fractional:Double = modf(integral,&integral);
 println(fractional);

---

只需要来自浮动的双倍内容

只需要integer的{​​{1}}值，然后

double

只需要 let integerValue:Int = Int(integral) println(integerValue) 的{​​{1}}值，然后

integer

Answer 2

假设您只使用字符串：

var str = "4.5 * 5.0 = 22.5 "

// Trim your string in order to remove whitespaces at start and end if there is any.
var trimmedStr = str.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
// Split the string by " " (whitespace)
var splitStr = trimmedStr.componentsSeparatedByString(" ")

// If the split was successful, retrieve the last past (your number result)
var lastPart = ""
if let result = splitStr.last {
    lastPart = result
}

// Since it's a XX.X number, split it again by "." (point)
var splitLastPart = lastPart.componentsSeparatedByString(".")

// If the split was successful, retrieve the last past (your number decimal part)
var decimal = ""
if let result = splitLastPart.last {
    decimal = result
}