Cocoa: change each character of a string to a different unicode value?

[retrotron]

I need to step through a string (character by character) and change each character to a different unicode value. How can I do that?

For example, suppose I have a string "abc" (unicode: x61 x62 x63). I want to step through each character in that string and change the unicode value to a different value: x44 x45 x46 ("DEF"). How do I do that?

 

[btoth]

There's a lot of different ways to do that. One way would be to get the C string version of the NSString (if your string is an NSString) and use a while loop to go through each element in the array. Or you could probably create a new NSMutableString and use characterAtIndex: for the original string and gradually build a new string from the old one. Or, if you use an NSMutableString to store the original string, you could use the replaceCharacters... method.

 

[retrotron]

Or you could probably create a new NSMutableString and use characterAtIndex: for the original string and gradually build a new string from the old one.

That sounds like a good approach. So once I get the characterAtIndex:, how do I put append a new unicode character to the new NSMutableString? I can't seem to figure out how to add a specific unicode character.

 

[btoth]

I'd probably just do something like this, but I haven't worked too much with unicode characters and I haven't actually tested this out.

unichar string[max_size];

[theString getCharacters:string];
/* that puts all the values into an array that you can go through */


/* store string back into NSString */
[string release];
[string = [[NSString stringWithCharacters:string length:strlen(string)] retain];

 

[macavenger]

I don't know if this works with unicode and cocoa, but in C++ you can simply add to a character. Is there something similar in cocoa? for instance, in C++ you can do something like

CharVariable=CharVariable+3;

which, if CharVariable was, say, A, would make CharVariable become D.

could you use the characterAtIndex: command in coca to do something similar? Like I said, I don't know, just a brainstorm. Hope this helps, sorry if it doesn't!

 

[retrotron]

Thanks all, this is all very helpful. What if I wanted to append the unicode character 0x03B2 to an NSMutableString. How would I do that?

 

[btoth]

I'm pretty sure (without looking at the documentation) you have to store the character into an NSString first, then append the NSString to the NSMutableString.

 

[retrotron]

Okay, I've got it working. Here's what I was looking for:

[someMutableString appendFormat:@"%C", 0x03B2];

Where 0x03B2 is the desired unicode character code.

Thanks!