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Re: Number of chars
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Re: Number of chars


  • Subject: Re: Number of chars
  • From: Roland King <email@hidden>
  • Date: Thu, 21 Mar 2013 17:47:28 +0800

On 21 Mar, 2013, at 5:07 PM, Luca Ciciriello <email@hidden> wrote:

> An example of string is the italian word "più".
> Here I can visually count 3 chars: p, i and ù. But if I use "più".size() the result is 4
>
> std::string ppp = "più";
> size_t sss = ppp.size();
>
> here sss is 4.
>
> L.
>

Not totally a cocoa question, it's really C++, if you were asking about the original NSString there are lots of cocoa methods to do things.

The size of a string in C++ is in bytes, so it all rather depends what encoding your string is in, which depends on how you're doing the conversion from NSString to C++, which I don't think you said.

My wild guess would be that it's UTF8, since you are getting 1-byte for most characters and 2-bytes for a  ù sounds correct for UTF8. What's the actual hex of those 4 characters for that string? 0x70 0x69 0xC3 0xB9 is I think the encoding for that.

If it is UTF8 then it's not so hard, just look at the encoding detail for UTF8 and you have to inspect the top bit or bits of each byte to determine whether or not it's a whole character, the start of a multibyte or a continuation of one. I would imagine there are C++ functions to do that. Also remember there is more than one way to produce a `, one is using the single unicode character for it, another is to use a combining diacritic mark and a 'u', that will be 4 unicode characters and, in UTF8, 5 bytes, for that string.
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References: 
 >Number of chars (From: Luca Ciciriello <email@hidden>)
 >Re: Number of chars (From: Luther Baker <email@hidden>)
 >Re: Number of chars (From: Luca Ciciriello <email@hidden>)

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