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Diffstat (limited to 'miralib/manual/31/9')
| -rw-r--r-- | miralib/manual/31/9 | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/miralib/manual/31/9 b/miralib/manual/31/9 new file mode 100644 index 0000000..8e6bb2d --- /dev/null +++ b/miralib/manual/31/9 @@ -0,0 +1,54 @@ +_I_n_p_u_t_/_o_u_t_p_u_t_ _o_f_ _b_i_n_a_r_y_ _d_a_t_a + +From version 2.044 Miranda stdenv.m includes a function + readb :: [char]->[char] +and new sys-message constructors + Stdoutb :: [char]->sys_message + Tofileb :: [char]->[char]->sys_message + Appendfileb :: [char]->[char]->sys_message + +These behave similarly to (respectively) read, Stdout, Tofile, +Appendfile but are needed in a UTF-8 locale for reading/writing binary +data (for further explanation see below). In a non UTF-8 locale they do +not behave differently from read, Stdout etc but you might still prefer +to use them for handling binary data, for portability reasons. + +The notation $:- is used for the binary version of the standard input. +In a non UTF-8 locale $:- and $- will produce the same results. It is +an error to access both $:- and $- in the same evaluation. + +_E_x_p_l_a_n_a_t_i_o_n + +The locale of a UNIX process is a collection of settings in the +environment which specify, among other things, what character encoding +is in use. To see this information use `locale' as a shell command. +The analogous concept in Windows is called a "code page". + +UTF-8 is a standard for encoding text from a wide variety of languages +as a byte stream, in which ascii characters (codes 0..127) are +represented by themselves while other symbols are represented by a +sequence of two or more bytes: a `multibyte character'. + +The Miranda type `char' consists of characters in the range (0..255) +where the codes above 127 represent various accented letters etc +according to the conventions of Latin-1 (i.e. ISO-8859-1, commonly used +for West European languages). There are national variants on Latin-1 +but since Miranda source, outside comments and string and character +constants, uses only ascii this does not normally cause a problem. + +In a UTF-8 locale: on reading string/character literals or text files +Miranda has to translate multibyte characters to the corresponding point +in the Latin-1 range (128-255). If the text does not conform to the +rules of UTF-8, or includes a character not present in Latin-1, an +"illegal character" error occurs. On output, Miranda strings are +translated back to UTF-8. + +If data being read/written is not text, but binary data of some kind, +translation from/to UTF-8 is not appropriate and could cause "illegal +character" errors, and/or corruption of data. Whence the need for the +byte oriented I/O functions readb etc, which transfer data without any +conversion from/to UTF-8. + +In a non UTF-8 locale read and readb, Tofile and Tofileb, etc. do not +differ in their results. + |