How to write a std string to a UTF-8 text file

Question

I just want to write some few simple lines to a text file in C    but I want them to be encoded in UTF-8  What is the easiest and simple way to do so

User · Answer

libiconv is a great library for all our encoding and decoding needs   If you are using Windows you can use WideCharToMultiByte and specify that you want UTF8

User · Answer

My preference is to convert to and from a std  u32string and work with codepoints internally  then convert to utf8 when writing out to a file using these converting iterators I put on github    include  lt utf utf h gt   int main         using namespace utf       u32string u32 text   U                do stuff with string        convert to utf8 string     utf32 to utf8 iterator lt u32string  iterator gt  pos u32 text begin         utf32 to utf8 iterator lt u32string  iterator gt  end u32 text end          u8string u8 text pos  end           write out utf8 to file

User · Answer

std  wstring text   L          QString qstr   QString  fromStdWString text   QByteArray byteArray qstr toUtf8         std  string str std  byteArray constData    byteArray length

User · Answer

What is the easiest and simple way to do so    The most intuitive and thus easiest handling of utf8 in C   is for sure using a drop-in replacement for std  string  As the internet still lacks of one  I went to implement the functionality on my own   tinyutf8  EDIT  now Github    This library provides a very lightweight drop-in preplacement for std  string  or std  u32string if you will  because you iterate over codepoints rather that chars   Ity is implemented succesfully in the middle between fast access and small memory consumption  while being very robust  This robustness to  invalid  UTF8-sequences makes it  nearly completely  compatible with ANSI  0-255    Hope this helps

User · Answer

The only way UTF-8 affects std  string is that size    length    and all the indices are measured in bytes  not characters   And  as sbi points out  incrementing the iterator provided by std  string will step forward by byte  not by character  so it can actually point into the middle of a multibyte UTF-8 codepoint   There s no UTF-8-aware iterator provided in the standard library  but there are a few available on the  Net   If you remember that  you can put UTF-8 into std  string  write it to a file  etc  all in the usual way  by which I mean the way you d use a std  string without UTF-8 inside    You may want to start your file with a byte order mark so that other programs will know it is UTF-8

User · Answer

Use Glib  ustring from glibmm   It is the only widespread UTF-8 string container  AFAIK   While glyph  not byte  based  it has the same method signatures as std  string so the port should be simple search and replace  just make sure that your data is valid UTF-8 before loading it into a ustring

User · Answer

There is nice tiny library to work with utf8 from c    utfcpp

User · Answer

As to UTF-8 is multibite characters string and so you get some problems to work and it s a bad idea  Instead use normal Unicode   So by my opinion best is use ordinary ASCII char text with some codding set  Need to use Unicode if you use more than 2 sets of different symbols   languages  in single    It s rather rare case  In most cases enough 2 sets of symbols  For this common case use ASCII chars  not Unicode    Effect of using multibute chars like  UTF-8 you get only China traditional  arabic or some hieroglyphic text  It s very very rare case      I don t think there are many peoples needs that  So never use UTF-8    It s avoid strong headache of manipulate such strings

User · Answer

If by  simple  you mean ASCII  there is no need to do any encoding  since characters with an ASCII value of 127 or less are the same in UTF-8

[c++] How to write a std::string to a UTF-8 text file

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