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Questions tagged [predefined-macro]

38 questions
55
votes
7 answers

How to use __DATE__ and __TIME__ predefined macros in as two integers, then stringify?

Want to use __ DATE __ and __ TIME __ as integer for giving automated version to my code in compile time. #define STRINGIZER(arg) #arg #define STR_VALUE(arg) STRINGIZER(arg) #define DATE_as_int_str useD(__DATE__) // What can be done…
Rick2047
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6 answers

How can I use #pragma message() so that the message points to the file(lineno)?

In order to add 'todo' items into my code, I want to put a message in the compiler output. I would like it to look like this: c:/temp/main.cpp(104): TODO - add code to implement this in order to make use of the Visual Studio build output…
xtofl
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2 answers

What is this #ifdef __GNUC__ about?

I've found these lines in the libmagic code. What do they mean? #ifdef __GNUC__ __attribute__((unused)) #endif What does __GNUC__ mean? It seems to check whether GCC is installed. What is __attribute__((unused))? There's a code snippet here but no…
alvas
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19
votes
5 answers

Detect ICC vs GCC at compile time

How to detect at compile time if I'm using gcc or icc? (I was quite puzzled to find out that icc defines __GNUC__ -- and even __GNUC_MINOR__ and __GNUC_PATCHLEVEL__ ! why?)
Znorg
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12
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3 answers

#error in Swift (how to mark compile-time error)

What is swift replacement of traditional c-style #error keyword? I need it to raise compile-time error when pre-defines failed: #if CONFIG1 ... #elseif CONFIG2 ... #else #error "CONFIG not defined" #endif
brigadir
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11
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1 answer

Are there any guarantees about consistency of __LINE__ directives?

GCC 9 has recently changed the behavior of the __LINE__ directive in some cases. The program below illustrates the change: #include #define expand() __LINE__ int main() { printf("%d\n",expand( )); return 0; } Because…
anol
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9
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1 answer

How to set predefined macros in Code::Blocks

Is there a way to set some predefined Macros for my local installation of Code::Blocks. To elaborate on that, basically I would like to have certain blocks compiled only at pc and not anyplace I send the code to. One way to achieve this is as…
Shamim Hafiz - MSFT
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9
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5 answers

How can I write a 'clamp' / 'clip' / 'bound' macro for returning a value in a given range?

I often find myself writing something like int computedValue = ...; return MAX(0, MIN(5, computedValue)); I would like to be able to write this as a single one-line macro. It must be free of side effects, in the same way that the existing system…
hfossli
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1 answer

__cplusplus < 201402L return true in gcc even when I specified -std=c++14

The directive: #ifndef __cplusplus #error C++ is required #elif __cplusplus < 201402L #error C++14 is required #endif The command-line: g++ -Wall -Wextra -std=c++14 -c -o header.o header.hpp My g++ version: g++ (tdm-1) 4.9.2 The error C++14 is…
DMaster
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4
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Make Visual Studio 2017 IDE #define __cplusplus when looking at header file

I'm using Visual Studio 2017 to work with an embedded project with both C and C++ files, and I'm using a C++ compiler for everything. When viewing a header file in the IDE, the predefined symbol __cplusplus is not defined. This affects the…
Tom the Toolman
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4
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2 answers

C++ get the month as number at compile time

I have a c++ project that has to print a revision string. The revision string is company wise specified and the protocol includes the build time as yyyy/mm/dd. I use to specify this as macro from the build system, but this is no longer an option…
gsf
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3
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2 answers

Detecting Aligned Memory requirement on target CPU

I'm currently trying to build a code which is supposed to work on a wide range of machines, from handheld pockets and sensors to big servers in data centers. One of the (many) differences between these architectures is the requirement for aligned…
Cyan
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3 answers

Is there a preprocessor macro that expands to the current selector?

Possible Duplicate: Dynamically retrieving current method's name Obj-C introspection: How can a method reference it's own selector? This applies to Objective-C, is there a preprocessor macro or something to get the SEL value of the current…
adib
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3
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1 answer

How to achieve a c++ macros like this

#define idebug(...) \ \#ifdef _DEBUG\ printf(__VA_ARGS__);\ \#endif\ #endif It is difficult to describe the intention, which generally means that i predefine a macros idebug which to save some code. If _ DEBUG flag is predefined, then print…
anti-gravity
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3
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2 answers

Linking to the correct library

I dont think my question here was answered here already. So here it is, I have a static library that I maintain and update periodically. I also update the version number correctly. Now my application which uses this library must link to…
Hari
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