How do you use parse string in swift?

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?

i mean if the result is 22.0 , i want just 22 not 22.0, of course if it is 22.5 , 0.5 will be there as a 22.5, but 0 of 22.0 for the result which is 22.0 or when typeing numbers 22.0 instead of 22 should not be on right side of point ? — legolas
– legolas, Commented Mar 3, 2015 at 0:52

lchamp · Accepted Answer · 2015-03-02 12:46:03Z

1

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
}

edited Mar 2, 2015 at 12:46

answered Mar 2, 2015 at 12:31

lchamp

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2 Comments

Airspeed Velocity Over a year ago

Instead of using a test of count followed by last!, you should use if let syntax: if let result = splitStr.last { lastPart = result }. ! is dangerous and should only be used when there’s no practical alternative.

Airspeed Velocity Over a year ago

NP. Also, check out Swift.split which is similar to componentsSeparatedByString: if let result = last(split(str) { $0 == " " }), let decimal = last(split(result) {$0 == "."}) { println(decimal) }

Paresh Navadiya · Accepted Answer · 2015-03-03 11:00:23Z

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)

edited Mar 3, 2015 at 11:00

answered Mar 2, 2015 at 12:10

Paresh Navadiya

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1 Comment

legolas Over a year ago

i mean if the result is 22.0 , i want just 22 not 22.0, of course if it is 22.5 , 0.5 will be there as a 22.5, but 0 of 22.0 for the result which is 22.0 or when typeing numbers 22.0 instead of 22 should not be on right side of point ?

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