How do I sscanf()?

Question

Created Nov ’15

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I'm trying to convert this to something usable in swift:

sscanf(scanStr, "%4d%2d%2dT%2d%2d%2d", &year, &month, &day, &hour, &minutes, &seconds

I explicitly do not want to use an NSDateFormatter as I have a bunch of different types I'm comparing against.

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Answer 1

DTS Engineer OP

Apple

Nov ’15

Accepted Answer

It’s not possible to call C varargs routines directly from Swift. In your specific case I’d probably use

strptime

. However, if you’re absolutely committed to

sscanf

then you’ll need to use C or Objective-C to write it in a Swift-compatible manner.

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Answer 2

CharlesS OP

Nov ’15

Well, technically you can via the varargs variants, but it's pretty unwieldy:

"20151130T052035".cStringUsingEncoding(NSUTF8StringEncoding)?.withUnsafeBufferPointer { buf in
    let scanStr = buf.baseAddress
   
    var year: Int32 = 0
    var month: Int32 = 0
    var day: Int32 = 0
    var hour: Int32 = 0
    var minutes: Int32 = 0
    var seconds: Int32 = 0
   
    withUnsafeMutablePointers(&year, &month, &day) { yearPtr, monthPtr, dayPtr in
        withUnsafeMutablePointers(&hour, &minutes, &seconds) { hourPtr, minPtr, secPtr in
            let args: [CVarArgType] = [yearPtr, monthPtr, dayPtr, hourPtr, minPtr, secPtr]
           
            if vsscanf(scanStr, "%4d%2d%2dT%2d%2d%2d", getVaList(args)) < 6 {
                print("Something went wrong!")
            } else {
                print("year: \(year) month: \(month) day: \(day) hour: \(hour) minutes: \(minutes) seconds: \(seconds)")
            }
        }
    }
}

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