macOS error: cannot find interface declaration for 'NXConstantString'

Hi


I am trying a code Kochan's book below and experience an error i cannot resolve:
error : cannot find interface declaration for 'NXConstantString'. This happens a few times, whenever NSLog line is called and whenever fileHandleForReadingAtPath is called.

can someone kindly explain y? Im using cygwin and pasted over the foundation libraries from GNUStep.


#import<Foundation/NSObject.h>
#import<Foundation/NSString.h>
#import<Foundation/NSFileHandle.h>
#import<Foundation/NSFileManager.h>
#import<Foundation/NSAutoreleasePool.h>
#import<Foundation/NSData.h>

int
main (int argc, const char *argv[])
{

NSAutoreleasePool *pool=[[NSAutoreleasePool alloc] init];
NSFileHandle *inFile,*outFile;
NSData *buffer;

//open the file test file for reading

inFile = [NSFileHandle
fileHandleForReadingAtPath "testfile"];

if (inFile==nil)
{ NSLog (@"Open of testfile for reading failed\n");
return 1;
}

//Create the output file first if necessary

[[NSFileManager defaultManager] createFileAtPath: @"testout"
contents:nil attributes: nil];

//Now open outfile for writing

outFile=[NSFileHandle fileHandleForWritingAtPath: @ "testout"];

if(outFile==nil)
{
NSLog(@"Open of Testout for writing failed\n");
return 2;
}

//Truncate the output file since it may contain data

[outFile truncateFileAtOffset: 0];

//Read the data from inFile and write it to outFile

buffer = [inFile readDataToEndOfFile];

[outFile writeData: buffer];

//Close the two files

[inFile closeFile];
[outFile closeFile];

[pool release];
return 0;


}
thanks
jeremy

I'm wondering if the file type to be read needs to be of a certain type?

as in txt file or something?