whoa that's one great answer. NOTE 2: the previous functions (get_classmate_path() and get_classmate_info_path()) may return NULL in case of errors. There are compilers that don't support it. In how many ways the letters of word 'PERSON' can be arranged in the following way. Why it is called "BatchNorm" not "Batch Standardize"? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What are some ways a planet many times larger than Earth could have a mass barely any larger than Earths? 2. is slow as std::to_string(age) creates a temporary string that is appended to the result. It's Java-style pseudocode. Do I owe my company "fair warning" about issues that won't be solved, before giving notice? rev2023.6.29.43520. Famous papers published in annotated form? (This is now a good canonical Q&A for this issue, though, so less-clear questions with less-good answers could be marked as duplicates of this.). A more general solution is: Thanks for contributing an answer to Stack Overflow! Making statements based on opinion; back them up with references or personal experience. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Asking for help, clarification, or responding to other answers. Difference between and in a sentence. In how many ways the letters of word 'PERSON' can be arranged in the following way. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The preprocessor does no such thing. How to set the default screen style environment to elegant code? Boost.Spirit Karma claims to be one of the fastest option for integer to string conversion. Cologne and Frankfurt). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Asking for help, clarification, or responding to other answers. not remember what version of gcc it was. How do I concatenate two string macros in C? Strings can simply be juxtaposed in C, and the compiler will concatenate them, which is what this macro does. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What do gun control advocates mean when they say "Owning a gun makes you more likely to be a victim of a violent crime."? The prime example is compiling X11, macro "Concat3" is broken, it's result is now MISNAMED C Identifier, which of course fails to build. Difference between and in a sentence. Apart from the one link you've gfiven, what are you basing your performance comments on? Uber in Germany (esp. Australia to west & east coast US: which order is better? This will tell you how to use snprintf, but I suggest a good C book! 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. 3 Answers Sorted by: 49 Try this #define space_conc (str1,str2) #str1 " " #str2 The '##' is used to concatenate symbols, not strings. Not the answer you're looking for? I'm trying to avoid having multiple occurrences of the "48" literal in my source, if the preprocessor can perform this substitution for me that would be great. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, Shouldn't it be #define STR3 STR1 ## STR2. 1960s? Instead of macros, you can do this with inline function. Why does the present continuous form of "mimic" become "mimicking"? @DD: D'oh, fixed now. What's the meaning (qualifications) of "machine" in GPL's "machine-readable source code"? why do you want to use macros so badly? I'm trying to do it by declaring a char* variable in macro 1 and use snprintf. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Concatenate string literal with char literal. How to define a C macro that uses another macro? @MSalters Thank you, this solves the first problem but does not solve the second one. Is there a variation to convert this to a wide string? How do I concatenate an integer onto a string in C? asprintf is part of the GNU C library extension and may not be available in other implementations. Find centralized, trusted content and collaborate around the technologies you use most. For what it's worth, with itoa/strcat you could do: Look at snprintf or, if GNU extensions are OK, asprintf (which will allocate memory for you). Is it legal to bill a company that made contact for a business proposal, then withdrew based on their policies that existed when they made contact? @Wossname: How are you going to use "basic" asm (without constraints) without stepping on the compiler's toes (i.e. There is the concatenate function. Teen builds a spaceship and gets stuck on Mars; "Girl Next Door" uses his prototype to rescue him and also gets stuck on Mars. Thanks for contributing an answer to Stack Overflow! It took me sometime to figure that out.. My brain hurts that this can't be done with a single macro As a lot of other people, used this dozens of times. Quick google gives, How Bloombergs engineers built a culture of knowledge sharing, Making computer science more humane at Carnegie Mellon (ep. Concatenation of const char* variables needs to happen at runtime, because character pointers (or any other pointers, for that matter) do not exist until the runtime. Other posters suggested using itoa. Not the answer you're looking for? Connect and share knowledge within a single location that is structured and easy to search. Does a constant Radon-Nikodym derivative imply the measures are multiples of each other? The first "STR_HELPER" is required because '#' only works with a macro argument. Australia to west & east coast US: which order is better? Do spelling changes count as translations for citations when using different English dialects? Making statements based on opinion; back them up with references or personal experience. There's a small constant bound on the size needed, so it makes much more sense to provide the buffer yourself. Frozen core Stability Calculations in G09? rev2023.6.29.43520. As soon as the ASM returns back to the C code all the memory used in the ASM is re-initialised. The #define directives define the identifier as macro, that is instruct the compiler to replace most successive occurrences of identifier with replacement-list, which will be additionally processed. How AlphaDev improved sorting algorithms? Do native English speakers regard bawl as an easy word? Do native English speakers regard bawl as an easy word? Mixing C and assembly sources and build with cmake. How do you build strings concatenated with int variables in C? like when they are used. I'd like to append a version number onto a string, but the only way I can get it to work is to make a copy of the version number defines as strings. How i can concatenate two integers into one integer. As it stands, the worst thing that will happen is that my xmas tree will stop flashing for a couple of seconds. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Creating macro using __LINE__ for different variable names, Create an identifier at compile time that has the line number as part of it, a macro substitution involving concatenation and line number, Using a macro expansion as part of an identifier, C++ the operator ## don't work with a string and a macro, C++ Token Pasting Operator not concatenating __LINE__ in pre-processor definition, Is there a way to concatenate __LINE__ and __COUNTER__ macros in c++, Concatanate macro argument with another token, Issue with concatenation using `##` operator, C language macro code - #define with 2 '##', Token concatenation using ## gives "not a valid preprocessing token", Make token concatenation before stringification in C macro, Creating C macro: concatenate string and number, C Preprocessor: concatenate macro call with token. Is there any advantage to a longer term CD that has a lower interest rate than a shorter term CD? If the argument passed to. For example, say we have two strings: "C programming" and "language". How to professionally decline nightlife drinking with colleagues on international trip to Japan? 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. For string variables, concatenation occurs only at run time. Exceptions arise from the rules of scanning and replacement. Why is inductive coupling negligible at low frequencies? A Chemical Formula for a fictional Room Temperature Superconductor, Difference between and in a sentence, Overline leads to inconsistent positions of superscript. Is there and science or consensus or theory about whether a black or a white visor is better for cycling? @AnttiHaapala--, itoa converts an int to a char string. So if A is defined as FRED, STRINGIZE_NX(A) expands to "A" but STRINGIZE(A) expands to STRINGIZE_NX(FRED) which expands to "FRED". Novel about a man who moves between timelines, Can't see empty trailer when backing down boat launch. Is there a way to use DNS to block access to my domain? How to define string literal with character type that depends on template parameter? why does music become less harmonic if we transpose it down to the extreme low end of the piano? Does the debt snowball outperform avalanche if you put the freed cash flow towards debt? Does a simple syntax stack based language need a parser? It did work, but using a Boost header in a C program seems kind of odd to me. For C++ instead of static you can use anonymous namespace: Finally, if you plan to use the string just to print it, or put it into a file, do not concatenate, but just do it in this function. Makes me smirk how people throw Boost at everything. There's no particular reason why the content of the string should be a valid C expression. It's not a problem that the earlier C pre-processors did not support UNIq_()__ because they supported #pragma which allows "compiler brand hackery in code to be flagged as hackery" and also function just as well WITHOUT effecting standards: just as changing defaults is useless wonton breakage, and just as changing what a function does while using the same name (namespace clobbering) is malware in my opinion. You misunderstand both my comment and the C language. I've tried it with just one, absent of # and ##, and that does not expand it on VS2017. What is the term for a thing instantiated by saying it? It permits separate tokens to be joined into a single token, and therefore, can't be the first or last token in the macro definition. how can i solve this problem preprocessor? How can I handle a daughter who says she doesn't want to stay with me more than one day? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Example #1 Here, the strings string_1 and string_2 get concatenated and the final result is stored in string_1. Any explanation of why you need 2 level of indirection? Why would a god stop using an avatar's body? Use sprintf (or snprintf if like me you can't count) with format string "pre_%d_suff". This is NOT a standard function, so your code will not be portable if you use it. Did the ISS modules have Flight Termination Systems when they launched? It doesn't work without the #s either because the values are numbers and it would expand to "/home/user/.myapp" 2 6, which isn't valid C. This does work, but I don't like having copies of the version defines because I do need them as numbers as well. Does a simple syntax stack based language need a parser? Can't see empty trailer when backing down boat launch. Placing a preprocessor directive inside a string literal? I am wondering if this solution will override the usual additions You are right (I just tested it). Step 2: Define three variables as String. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. In C++11, you can use std::to_string, e.g. By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. Please help us improve Stack Overflow. Converting a #defined constant number to a string, C preprocessor - Prepending path for existing define. What should be included in error messages? The double-number-sign or token-pasting operator ( ## ), which is sometimes called the merging or combining operator, is used in both object-like and function-like macros. The syntax is like below: #define STR1 "str1" #define STR2 " str2" #define STR3 STR1 STR2 //it will concatenate str1 and str2 Input: Take two strings Output: Return concatenated string. Why would a god stop using an avatar's body? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Why would a god stop using an avatar's body? I'm trying to define a macro which is suppose to take 2 string values and return them concatenated with a one space between them. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. Can't see empty trailer when backing down boat launch. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. Did the ISS modules have Flight Termination Systems when they launched? ## concatenated tokens in macro during the preprocessing stage (ie before C code compilation).## does something completely different than a concatenation of the adjacent string literals (both have to be string . The following definition for static_assert () from DCL03-C. Use a static assertion to test the value of a constant expression uses the JOIN () macro to concatenate the token assertion_failed_at_line_ with the value of __LINE__: #define static_assert (e) \ typedef char JOIN (assertion_failed_at_line_, __LINE__) \ [ (e) ? Is there a way to use DNS to block access to my domain? Thanks for contributing an answer to Stack Overflow! "foo" "bar" is the same as "foobar". Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Cologne and Frankfurt). Hi @vitaut, does fmt::format supports dynamic inputstring? Thanks for contributing an answer to Stack Overflow! How do I concatenate two string macros in C? Allocating the memory "for you" is hardly doing you a favor. Is it usual and/or healthy for Ph.D. students to do part-time jobs outside academia? It's only working for char literals that they can be concatenated in this way: This will not work for a pointer expression which you have in your sample, which expands to a statement like, As for your edit: Can one be Catholic while believing in the past Catholic Church, but not the present? Do native English speakers regard bawl as an easy word? What do you do with graduate students who don't want to work, sit around talk all day, and are negative such that others don't want to be there? It's more than a technicality - you can't concatenate. How could a language make the loop-and-a-half less error-prone? So then this: My tendency would be to never use sprintf, since this can result in buffer-overflows. This is not C. Or C++. But you're right to raise this point, if I were to make a habit of using AVR assembly (not likely) then I would certainly look into the correct way to do things. Thanks 10-15-2014 #2 Matticus Registered User Join Date Jun 2011 Posts 4,512 How do I concatenate two string macros in C? Why would a god stop using an avatar's body? Other than heat. Can renters take advantage of adverse possession under certain situations? To learn more, see our tips on writing great answers. Is it possible to "get" quaternions without specifically postulating them? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. How do you append an int to a string in C++? How Bloombergs engineers built a culture of knowledge sharing, Making computer science more humane at Carnegie Mellon (ep. As for the second example, you probably want: #define CAT_ (A,B) A##B #define CAT (A,B) CAT_ (A,B) #define GAP 2 #define VERSION CAT (VERSION_WLT_GAP_ , GAP) VERSION //expands to VERSION_WLT_GAP_2. concatenates two tokens in a macro invocation (text and/or arguments) given in a macro definition. It needs 2 layers of indirection, not 1. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 3 Answers Sorted by: 216 If they're both strings you can just do: #define STR3 STR1 STR2 This then expands to: #define STR3 "s" "1" and in the C language, separating two strings with space as in "s" "1" is exactly equivalent to having a single string "s1". Note that snprintf is not guaranteed to null-terminate the string. It's the C language proper that treats adjacent string literals as if they were a single string literal. Other than heat. The first step to concatenating int variable and the character string is to convert an integer to string. Can't see empty trailer when backing down boat launch. If a polymorphed player gets mummy rot, does it persist when they leave their polymorphed form? Let's see the example to concatenate two strings manually without using strcat () function. Overline leads to inconsistent positions of superscript. Here is what I wrote so far which does not work. Find centralized, trusted content and collaborate around the technologies you use most. My compiler is GCC 4.1 on CentOS 5. This problem can be done in many ways. I'm trying to figure out how I can concatenate a #define'd int to a #define'd string using the C Preprocessor. :). Technically string concatenation is done at the language level. the string is not forming or what? How to append two #define together as keywords in C? Is it usual and/or healthy for Ph.D. students to do part-time jobs outside academia? I'm not at all familiar with the magic of inlining AVR assembly code into AVR Studio's GCC compiler. Wanted to know how to do that symbol concatenation. Q&A for work. Well, the answer seems to be the following: which produces V008.1-11-g68a9c89cb4-dirty_COMPDEP_WLT:G2 and I am happy with it. I'll look into it in a bit and update my question accordingly. Australia to west & east coast US: which order is better? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, show us what you've tried instead of what you want, you'll learn much more with comments on your code than people telling you what to do. : If you have Boost, you can convert the integer to a string using boost::lexical_cast
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c macro: concatenate string and int
