trigraphs i know it's a set of three letters that get treats as they ware one letter
but how does it help me !!
i am confusing about that
in the tutorial he said that there is different character sets the one that programs are written in and the one that programs execute with how could that be ?
i mean when i write this
printf("Nothing");
it turns into another character set ? so my question is
why to use trigraphs?
thanks
From http://en.wikipedia.org/wiki/C_trigraph:
The reason for their existence is that the basic character set of C is a subset of the ASCII character set (nine of its characters lie outside the smaller ISO 646 invariant character set). This can pose a problem for writing source code if the keyboard being used does not support any of these nine characters. The ANSI C committee invented trigraphs as a way of entering source code using keyboards that supported any version of the ISO 646 character set. Non-ASCII ISO 646 character sets are not much used today, but trigraphs remain in the C standard.
"Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
-Christopher Hitchens
wow
that's why my compiler witch i really hate "dev cpp" gives me errorsTrigraphs are not commonly encountered outside compiler test suites. Some compilers either have an option to turn recognition of trigraphs off, or disable trigraphs by default and require an option to turn them on. Some can issue warnings when they encounter trigraphs in source files.
thanks for the link
GCC supports trigraphs but they are not enabled by default. You can use either the -ansi or -trigraphs options to enable them.
-ansi
In C mode, support all ISO C90 programs. In C++ mode, remove GNU
extensions that conflict with ISO C++.
This turns off certain features of GCC that are incompatible with
ISO C90 (when compiling C code), or of standard C++ (when compiling
C++ code), such as the "asm" and "typeof" keywords, and predefined
macros such as "unix" and "vax" that identify the type of system
you are using. It also enables the undesirable and rarely used ISO
trigraph feature. For the C compiler, it disables recognition of
C++ style // comments as well as the "inline" keyword.Edit: BTW, you shouldn't care about trigraphs unless you actually have one of these ancient keyboards. But the -ansi option is useful, since it's a good idea to use the options "-W -Wall -ansi -pedantic" to turn on lots of useful warnings.-trigraphs
Support ISO C trigraphs. The -ansi option (and -std options for
strict ISO C conformance) implies -trigraphs.
Last edited by robatino; 06-21-2007 at 01:03 PM.
