你如何在swift中使用解析字符串？

Question

An issue here to me that if i use parse string for the result of calculator program for instance,

4.5 * 5.0 = 22.5 

how can I use splitting here to depart decimal part from result?

Answer 1

Use modf to extract decimal part from result.

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);

---

Want only interger part from double of float

Want only integer value from double then

 let integerValue:Int = Int(integral)
 println(integerValue)

Want only integer value from float then

 let integerValue:Float = Float(integral)
 println(integerValue)

Answer 2

Assuming you're working with strings only :

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
}