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<HTML><HEAD> <TITLE>BBS水木清华站∶精华区</TITLE></HEAD><BODY><CENTER><H1>BBS水木清华站∶精华区</H1></CENTER>LANGUAGE OPTIONS <BR> The following options control the dialect of C that the <BR> compiler accepts: <BR> <BR> -ansi Support all ANSI standard C programs. <BR> <BR> This turns off certain features of GNU C that are <BR> incompatible with ANSI C, such as the asm, inline <BR> and typeof keywords, and predefined macros such as <BR> unix and vax that identify the type of system you <BR> are using. It also enables the undesirable and <BR> rarely used ANSI trigraph feature, and disallows <BR> `$' as part of identifiers. <BR> <BR> The alternate keywords __asm__, __extension__, <BR> __inline__ and __typeof__ continue to work despite <BR> `-ansi'. You would not want to use them in an ANSI <BR> C program, of course, but it is useful to put them <BR> in header files that might be included in compila- <BR> tions done with `-ansi'. Alternate predefined <BR> macros such as __unix__ and __vax__ are also avail- <BR> able, with or without `-ansi'. <BR> <BR> <BR> The `-ansi' option does not cause non-ANSI programs <BR> to be rejected gratuitously. For that, `-pedantic' <BR> is required in addition to `-ansi'. <BR> <BR> The preprocessor predefines a macro __STRICT_ANSI__ <BR> when you use the `-ansi' option. Some header files <BR> may notice this macro and refrain from declaring <BR> certain functions or defining certain macros that <BR> the ANSI standard doesn't call for; this is to <BR> avoid interfering with any programs that might use <BR> these names for other things. <BR> <BR> -fno-asm <BR> Do not recognize asm, inline or typeof as a key- <BR> word. These words may then be used as identifiers. <BR> You can use __asm__, __inline__ and __typeof__ in- <BR> stead. `-ansi' implies `-fno-asm'. <BR> <BR> -fno-builtin <BR> Don't recognize built-in functions that do not be- <BR> gin with two leading underscores. Currently, the <BR> functions affected include _exit, abort, abs, allo- <BR> ca, cos, exit, fabs, labs, memcmp, memcpy, sin, <BR> sqrt, strcmp, strcpy, and strlen. <BR> <BR> The `-ansi' option prevents alloca and _exit from <BR> being builtin functions. <BR> <BR> -fno-strict-prototype <BR> Treat a function declaration with no arguments, <BR> such as `int foo ();', as C would treat it--as say- <BR> ing nothing about the number of arguments or their <BR> types (C++ only). Normally, such a declaration in <BR> C++ means that the function foo takes no arguments. <BR> <BR> -trigraphs <BR> Support ANSI C trigraphs. The `-ansi' option im- <BR> plies `-trigraphs'. <BR> <BR> -traditional <BR> Attempt to support some aspects of traditional C <BR> compilers. For details, see the GNU C Manual; the <BR> duplicate list here has been deleted so that we <BR> won't get complaints when it is out of date. <BR> <BR> But one note about C++ programs only (not C). <BR> `-traditional' has one additional effect for C++: <BR> assignment to this is permitted. This is the same <BR> as the effect of `-fthis-is-variable'. <BR> <BR> -traditional-cpp <BR> Attempt to support some aspects of traditional C <BR> preprocessors. This includes the items that <BR> specifically mention the preprocessor above, but <BR> none of the other effects of `-traditional'. <BR> <BR> -fdollars-in-identifiers <BR> Permit the use of `$' in identifiers (C++ only). <BR> You can also use `-fno-dollars-in-identifiers' to <BR> explicitly prohibit use of `$'. (GNU C++ allows <BR> `$' by default on some target systems but not oth- <BR> ers.) <BR> <BR> -fenum-int-equiv <BR> Permit implicit conversion of int to enumeration <BR> types (C++ only). Normally GNU C++ allows conver- <BR> sion of enum to int, but not the other way around. <BR> <BR> -fexternal-templates <BR> Produce smaller code for template declarations, by <BR> generating only a single copy of each template <BR> function where it is defined (C++ only). To use <BR> this option successfully, you must also mark all <BR>
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