NSString

Strings in GNUstep use the NSString class in gnustep-base. See the reference manual for gnustep-base for more details about NSString.

Constructing Strings

As you can create static instances of char* plain C, you can create strings in GNUstep that automatically flatten out to be static instances of NSString. This is done by preceding the quoted string by an "at" symbol ('@'). For example:

 NSString * myString = @"This is an example of a string.";
 NSLog(myString);

myString is now an NSString object, and can have methods called on it like any other string.

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You can also make a copy of a string as shown in the following example:

 NSString *myString = @"This is an example of a string.";
 NSString *newString = [NSString stringWithString: myString];

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Or if you already have a C string you can convert it to a NSString object as follows:

 char *myString = "This is a C string.";
 ...
 NSString *NSString newString1 = [NSString stringWithCString: myString encoding: [NSString defaultCStringEncoding]];
 // Or:
 NSString *NSString newString2 = [NSString stringWithUTF8String: myString];

Note that using [NSString stringWithCString] is deprecated!

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A more flexable way of creating a string, using C style format flags follows:

 NSString *myString = [NSString stringWithFormat: @"This is an%@ of a string with %d integer.", @" example", 1];

Getting a C String

You can convert an NSString object to a plain C string using the cStringUsingEncoding: method. For example:

 NSString *newString = @"This is a test string.";
 char     *theString;

 theString = [newString cStringWithEncoding:[NSString defaultCStringEncoding]];

or:

 theString = [newString UTF8String];

Note that using [string cString] is deprecated!

Reading and Writing Files With String

The following example shows how you would use files with NSString:

 // Read in the file.
 NSString *aString = [NSString stringWithContentsOfFile: @"infile.txt"];
 // Do something with our new string.
 aString = doSomething(aString);
 // And finally save our changes to a file.
 if([aString writeToFile: @"outfile" atomically: YES])
   // Success code.
 else
   // Error code.