[swift-users] Simple text file I/O with Swift 3

[Ken Burgett]

Sorry, that does not compile with Swift 3. First of all, the expression 
"(count:BUFSIZE, repeatedValue:CChar(0))" must be written as 
"(repeating:CChar(0), count:BUFSIZE)", Note that the order within the 
expression is significant (don't ask me why, it just is.  Ask the 
language designers).

Second, print line causes the compiler to disgorge the following:
" error: 'fromCString' is unavailable: Please use 
String.init?(validatingUTF8:) instead. Note that it no longer accepts 
NULL as a valid input. Also consider using String(cString:), that will 
attempt to repair ill-formed code units.
     print(String.fromCString(buf)!, terminator:"")
                  ^~~~~~~~~~~
Swift.String:4:24: note: 'fromCString' has been explicitly marked 
unavailable here
     public static func fromCString(_ cs: UnsafePointer<CChar>) -> 
String?
"

I frankly don't know how to parse that compiler output, since it is NOT 
like Swift 2.2, and is apparently trying to explain that in some 
tortured form of syntax.  I don't know how to map that response into 
working code.

On 2016-05-28 18:54, TUNG CK wrote:
> Same as Linux 2.2
> 
> import Glibc
> 
> let path = "./sample.txt"
> let BUFSIZE = 1024
> 
> let fp = fopen(path, "r")
> if fp != nil {
>   var buf = [CChar](count:BUFSIZE, repeatedValue:CChar(0))
>   while fgets(&buf, Int32(BUFSIZE), fp) != nil {
>     print(String.fromCString(buf)!, terminator:"")
>   }
> }
> 
> 
>> Ken Burgett via swift-users <swift-users at swift.org> 於 29 May 2016 2:05 
>> AM 寫道：
>> 
>> Hi all,
>> 
>> I am trying to understand how Swift 3 File I/O works in a linux 
>> environment.  I put together a trivial test program using what I
>> can glean from the few examples I can find.  See below.
>> 
>> ===============================
>> import Glibc
>> import Foundation
>> 
>> let filename = Process.arguments[1]
>> let file_handle = fopen (filename, "r")
>> let BUFSIZE = 1024
>> var buf     = [CChar](repeating:CChar(0), count:BUFSIZE)
>> while fgets(&buf, Int32(BUFSIZE), file_handle) != nil
>> {
>>  print(buf)
>> }
>> exit(0)
>> ===============================
>> 
>> The program runs, but produces a stream of integer arrays, each of 
>> 1024 bytes.  I can see what appears to be ASCII character values in 
>> the sample text, plus a lot of trailing zeros.  I suspect I haven't 
>> mapped the bytes in buf to Strings, so how should that be done?
>> --
>> Ken Burgett
>> Principal Software Engineer
>> Email: kenb at iotone.io
>> Office: 530.693.4449
>> Mobile: 831.332.6846
>> URL: www.iotone.co
>> <main.swift>
>> _______________________________________________
>> swift-users mailing list
>> swift-users at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-users

-- 
Ken Burgett
Principal Software Engineer
Email: kenb at iotone.io
Office: 530.693.4449
Mobile: 831.332.6846
URL: www.iotone.co