Replace character in string

Question

I have a NSMutableString @"hello". I'd like to replace the character at the second position, 'e' with 'a' so that it reads @"hallo". How do I do that?

I have tried this to implement a Shift Cipher, but it throws an IndexOutBoundsException

- (NSString*)encode:(NSString*)original withShift:(int)shift {

    NSMutableString* encoded = [NSMutableString stringWithString:original];
    for (int i=0; i < [encoded length]; i++) {
        char oriChar = [encoded characterAtIndex:i];
        if (oriChar == ' ') {
            continue;
        }
        char encChar = ((oriChar - LETTER_POS) + shift) % ALPHABET_LENGTH + LETTER_POS;

        NSRange range = {i, i};
        [encoded replaceCharactersInRange:range withString:[NSString stringWithUTF8String:&encChar]];

    }
    return encoded;

}

possible duplicate of [Replacing one character in a string - iPhone/iPad](http://stackoverflow.com/questions/5223701/replacing-one-character-in-a-string-iphone-ipad) — jscs, Oct 29 '11 at 16:59

score 3 · Accepted Answer · answered Oct 29 '11 at 16:36

3

NSRange r = {1,1}; //String indexing is 0-based
[s replaceCharactersInRange: r withString:@"a"]

Also, do learn to use the online reference.

answered Oct 29 '11 at 16:36

Seva Alekseyev

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Or use [AppKiDo](http://homepage.mac.com/aglee/downloads/appkido.html) for reference, it's free and uses the Apple documentation. – zaph Oct 29 '11 at 16:39

score 2 · Answer 2 · answered Oct 29 '11 at 16:31

2

You can use stringByReplacingOccurrencesOfString:withString: of NSString.

answered Oct 29 '11 at 16:31

Cesar A. Rivas

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I see. Can I replace the character only at a specified index? – siamii Oct 29 '11 at 16:33
use 'stringByReplacingOccurrencesOfString:withString:options:range:' instead. – Cesar A. Rivas Oct 29 '11 at 16:35

Replace character in string

2 Answers2

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