NSString to ASCII

NSString *field = @"some string";
for(int i=0; i<\[field length\]; ++i)
{
unichar c = \[field characterAtIndex:i\];
NSLog(@"decimal char %d", c);
}

unichar is typed as unsigned short so this works fine.

Hi Martin. Read up on NSString. It's an object for handling Unicode strings, and it's quite different from a C-string, though it includes methods for converting to and from C-strings.

- (IBAction)test1:(id)sender {
 NSString *field = @"kabc"; // '@' operator changes C-string to NSString constant
 int length = [field length]; // obtain length of NSString
 int i = (length <= 5 ? 0 : length - 5); // don't allow index to go below zero 
 for (; i < length; ++i) {
 int c = [field characterAtIndex:i]; // type int; for your purposes int is ok for unichar
 //
 // not sure what the next 2 lines are for, they're not relevant to your question anyway
 // int j = (int) c;
 // fAscii = fAscii + j;
 //
 NSLog(@"char %d = %d", i, c);
 }
}

If the input string will be typed by international users (whether or not you localize your app), remember that the int values obtained from the string won't be restricted to the ASCII range. These ints can range from 0 to 65535, so you'll want to decide what to do with ints > 127. If you're doing something like a checksum you might just want c=c%127; or whatever.

Ooops.. I sure didn't mean to repeat your solution, jtgrassie!! No matter how old a thread may be, I seem to have the amazing ability to cause other developers to respond to it while I'm editing my post. I try to refresh the forum page immediately before clicking Post Message, but I often don't see the prior response until afterwards. I guess it never hurts to have two identical opinions, just I feel like an idiot.

No offence taken RayNewbie 🙂
Your post was more explanatory than mine anyway!

Sorry, I don't understand your question. Please give examples of input and output like this:

"k" => "108"
"ka" => "108097"
"ka" => "10897"
"ka" => "108.097"
"ka" => {108, 97}
"ka" => "6B61"
"ka" => {6B, 61}
"ka" => ???

krtek wrote:
I need connecting this four numbers (107,97,98,99) to one number or string.

Please show me exactly what the one resulting number would be, or what the string would look like.

E.g., do you want to form the decimal number 107979899 or the string "107979899" ? Or would you want the number 107097098099 ? Note that not all concatenations will allow you to recover the original numbers, in case that matters. Will you need to encode strings longer than four? Are the chars in the string limited to ASCII? If not, what is the char set?

In any case. I need a precise specification so we don't waste any more time, ok?

- (unsigned long long)encodeString:(NSString*)field {
 NSMutableString *digitString = [NSMutableString stringWithCapacity:18];
 for (int i = 0; i < [field length]; i++) {
 int c = [field characterAtIndex:i];
 NSLog(@"char %d = %d", i, c); 
 [digitString appendFormat:@"%d", c];
 }
 if ([digitString length] > 18) {
 // decimal value will overflow unsigned 64 bit integer
 NSLog(@"encodeString: Overflow");
 // digitString could be truncated here if desired
 return 0;
 }
 return [digitString longLongValue];
}
- (IBAction)test {
 unsigned long long myResult = [self encodeString:@"kabc"];
 NSLog(@"myResult=%qu", myResult);
 myResult = [self encodeString:@"kabcéák"];
 NSLog(@"myResult=%qu", myResult);
}

[Session started at 2009-05-29 22:41:40 -0700.]
2009-05-29 22:43:16.072 TestBed[39806:20b] char 0 = 107
2009-05-29 22:43:16.072 TestBed[39806:20b] char 1 = 97
2009-05-29 22:43:16.072 TestBed[39806:20b] char 2 = 98
2009-05-29 22:43:16.075 TestBed[39806:20b] char 3 = 99
2009-05-29 22:43:16.075 TestBed[39806:20b] myResult=107979899
2009-05-29 22:43:16.075 TestBed[39806:20b] char 0 = 107
2009-05-29 22:43:16.076 TestBed[39806:20b] char 1 = 97
2009-05-29 22:43:16.076 TestBed[39806:20b] char 2 = 98
2009-05-29 22:43:16.076 TestBed[39806:20b] char 3 = 99
2009-05-29 22:43:16.077 TestBed[39806:20b] char 4 = 233
2009-05-29 22:43:16.077 TestBed[39806:20b] char 5 = 225
2009-05-29 22:43:16.077 TestBed[39806:20b] char 6 = 107
2009-05-29 22:43:16.078 TestBed[39806:20b] myResult=107979899233225107