#ifdef Error Warning
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message. You would use ‘#error’ inside of #error in c a conditional that detects a combination of
Gcc #message
parameters which you know the program does not properly support. For #error c++ example, if you know that the program will not run properly on a VAX, you might write #ifdef __vax__ c preprocessor message #error "Won't work on VAXen. See comments at get_last_object." #endif If you have several configuration parameters that must be set up by the installation in a consistent way, you can use conditionals to detect an inconsistency and report
Gcc #warning Directive
it with ‘#error’. For example, #if !defined(FOO) && defined(BAR) #error "BAR requires FOO." #endif The directive ‘#warning’ is like ‘#error’, but causes the preprocessor to issue a warning and continue preprocessing. The tokens following ‘#warning’ are used as the warning message. You might use ‘#warning’ in obsolete header files, with a message directing the user to the header file which should be used instead. Neither ‘#error’ nor ‘#warning’ macro-expands its argument. Internal whitespace sequences are each replaced with a single space. The line must consist of complete tokens. It is wisest to make the argument of these directives be a single string constant; this avoids problems with apostrophes and the like.
tokens Description #error emits tokens to standard error, and increments the assembler error counter, hereby preventing the program from being successfully assembled. #error is specified in #error in c example the ANSI C standard. #warning emits tokens to standard error, and #error gcc increments the assembler warning counter. #warning is not specified in the ANSI C standard, but is commonly implemented
Error Directive Must Use C++ For The Type Iostream
in preprocessors such as the GNU C preprocessor. #message emits tokens to standard output, and does not affect assembler error or warning counters. #message is not specified in the https://gcc.gnu.org/onlinedocs/cpp/Diagnostics.html ANSI C standard.For all directives, the output will include file name and line number, like normal error and warning messages.tokens is a sequence of preprocessor tokens. Preprocessor macros are expanded except if appearing inside quoted strings (").Example #error "Unsupported part:" __PART_NAME__ PrevUpNextHomeContentsSearchDocumentation HomeAVR AssemblerPrefaceAVR Assembler Known IssuesAVR Assembler Command Line OptionsAssembler sourceAVR Assembler SyntaxAssembler directivesAVR Assembler PreprocessorIntroductionPreprocessor directives#define#undef#ifdef#ifndef#if http://www.atmel.com/webdoc/avrassembler/avrassembler.wb_preprocessor.error.html and #elif#else#endif#error, #warning and #message#include#pragma, general purpose#pragma , AVR part related# (empty directive)OperatorsStringification (#)Concatenation (##)Pre-defined macrosExpressionsInstruction mnemonicsArithmetic and logic instructionsBranch InstructionsData Transfer InstructionsBit and Bit-test InstructionsI/O RegistersInstruction Set Nomenclature:Instructions ADC - Add with Carry ADD - Add without Carry ADIW - Add Immediate to Word AND - Logical AND ANDI - Logical AND with Immediateand ASR - Arithmetic Shift Right BCLR - Bit Clear in SREG BLD - Bit Load from the T Flag in SREG to a Bit in Register. BRBC - Branch if Bit in SREG is Cleared BRBS - Branch if Bit in SREG is Set BRCC - Branch if Carry Cleared BRCS - Branch if Carry Set BREAK - Break BREQ - Branch if Equal BRGE - Branch if Greater or Equal Signed) BRHC - Branch if Half Carry Flag is Cleared BRHS - Branch if Half Carry Flag is Set BRID - Branch if Global Interrupt is Disabled BRIE - Branch if Global Interrupt is Enabled BRLO - Branch if Lower (Unsigned) BRLT - Branch if Le
your question and get tips & solutions from a community of 418,438 IT Pros & Developers. It's quick & easy. printing a warning with the preprocessor P: n/a Shea Martin I would like to issue a warning with the https://bytes.com/topic/c/answers/136317-printing-warning-preprocessor preprocessor: #ifdef _A_DEFINE && OTHER_DEFINE #print "_A_DEFINE and OTHER_DEFINE cannot both be defined" #print "OTHER_DEFINE will https://en.wikipedia.org/wiki/C_preprocessor be undefined for you" #endif I realize that the above example may created some unexpected behavoir, but the situation in which I am actually using it makes sense. I have tried using #error "my message", but this causes the CPP to abort, I just want a warning printed. I also tried #warn "my message", but this is not recognized my Sun's CPP. Thanks, ~S Jul #error in 22 '05 #1 Post Reply Share this Question 8 Replies P: n/a Victor Bazarov Shea Martin wrote: I would like to issue a warning with the preprocessor: #ifdef _A_DEFINE && OTHER_DEFINE #print "_A_DEFINE and OTHER_DEFINE cannot both be defined" #print "OTHER_DEFINE will be undefined for you" #endif I realize that the above example may created some unexpected behavoir, but the situation in which I am actually using it makes sense. I have tried using #error "my message", but this causes the #error in c CPP to abort, I just want a warning printed. I also tried #warn "my message", but this is not recognized my Sun's CPP. Well, it's a good hint for you to RTFM on your compiler, isn't it? Some compilers have '#pragma message' but I don't know about Sun's. Like I said, RTFM. V Jul 22 '05 #2 P: n/a Dave O'Hearn Shea Martin wrote: I also tried #warn "my message", but this is not recognized my Sun's CPP. Try #warning instead of #warn. -- Dave O'Hearn Jul 22 '05 #3 P: n/a Shea Martin Victor Bazarov wrote: Shea Martin wrote: I would like to issue a warning with the preprocessor: #ifdef _A_DEFINE && OTHER_DEFINE #print "_A_DEFINE and OTHER_DEFINE cannot both be defined" #print "OTHER_DEFINE will be undefined for you" #endif I realize that the above example may created some unexpected behavoir, but the situation in which I am actually using it makes sense. I have tried using #error "my message", but this causes the CPP to abort, I just want a warning printed. I also tried #warn "my message", but this is not recognized my Sun's CPP. Well, it's a good hint for you to RTFM on your compiler, isn't it? Some compilers have '#pragma message' but I don't know about Sun's. Like I said, RTFM. V Well I RTFM for CPP(2) and for for the compiler's pragma-appendix before I posted, so that I wouldn't be condescended upon... Anyway, #pragma message is
article is written like a manual or guidebook. Please help rewrite this article from a descriptive, neutral point of view, and remove advice or instruction. (February 2013) (Learn how and when to remove this template message) This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. (March 2015) (Learn how and when to remove this template message) (Learn how and when to remove this template message) The C preprocessor or cpp is the macro preprocessor for the C and C++ computer programming languages. The preprocessor provides the ability for the inclusion of header files, macro expansions, conditional compilation, and line control. In many C implementations, it is a separate program invoked by the compiler as the first part of translation. The language of preprocessor directives is only weakly related to the grammar of C, and so is sometimes used to process other kinds of text files. Contents 1 Phases 1.1 Including files 1.2 Conditional compilation 1.3 Macro definition and expansion 1.4 Special macros and directives 1.4.1 Token stringification 1.4.2 Token concatenation 1.5 User-defined compilation errors 2 Implementations 2.1 Compiler-specific preprocessor features 3 Other uses 4 See also 5 References 6 External links Phases[edit] Preprocessing is defined by the first four (of eight) phases of translation specified in the C Standard. Trigraph replacement: The preprocessor replaces trigraph sequences with the characters they represent. Line splicing: Physical source lines that are continued with escaped newline sequences are spliced to form logical lines. Tokenization: The preprocessor breaks the result into preprocessing tokens and whitespace. It replaces comments with whitespace. Macro expansion and directive handling: Preprocessing directive lines, including file inclusion and conditional compilation, are executed. The preprocessor simultaneously expands macros and, in the 1999 version of the C standard,[clarification needed] handles _Pragma operators. Including files[edit] One of the most common uses of the preprocessor is to include another file: #include