By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Find centralized, trusted content and collaborate around the technologies you use most. The preprocessor does no such thing. 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. Here is a task that asks you to put/get classmate's information into/from in info.txt under each classmate's folder, for example: I attempted to define those attributes with define macro: Obviously, the second macro is wrong because it's not allowed to concatenate symbolic constant, in this case CLASS_PATH, with const char* by using ## operator. How do you get assembler output from C/C++ source in GCC? How Bloombergs engineers built a culture of knowledge sharing, Making computer science more humane at Carnegie Mellon (ep. Your macro is pretty unnecessary, as it can only work with string literals of the same type. Even there is a separate function for concatenation in worksheet functions. Can renters take advantage of adverse possession under certain situations? 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? Mixing C and assembly sources and build with cmake. How to add a number to a string at the end in a c program? Do native English speakers regard bawl as an easy word? How should I ask my new chair not to hire someone? why does music become less harmonic if we transpose it down to the extreme low end of the piano. Concatenation involves appending one string to the end of another string. Making statements based on opinion; back them up with references or personal experience. Not the answer you're looking for? The '+' operator adds the two input strings and returns a new string that contains the concatenated string. Concatenation operators join multiple strings into a single string. It shouldn't be either because that defines STR3 to be the preprocessing token STR1STR2. on the line number. will expand it once and check it for validity, discard that, and then expand it again into a string. string concatenation in macro C Ask Question Asked 6 years, 7 months ago Modified 6 years, 7 months ago Viewed 1k times -3 In C, I have two macros Edit: #define macro1 (name , number , date ) {\ <---------body------> } #define macro2 (key) {\ <------body-----> } The reason the macro works is that C++ standard treats adjacent string literals like a single string literal. With, How Bloombergs engineers built a culture of knowledge sharing, Making computer science more humane at Carnegie Mellon (ep. 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". To learn more, see our tips on writing great answers. Can renters take advantage of adverse possession under certain situations? @5gon12eder - both "static inline" will not compile on C++. I prompt an AI into generating something; who created it: me, the AI, or the AI's author? I use macros to concatenate strings, such as: which having STRCAT(STR1 , STR2 ) produces "firstsecond". I want to create a C macro that creates a function with a name based Modifying strings is an important programming skill. You can concatenate int to string by using the given below simple trick, but note that this only works when integer is of single digit. The preprocessor directive ## (two hashes or number signs, aka the token pasting operator) allows to concatenate two symbols into one. Novel about a man who moves between timelines. sure. can be useful if you wish to hide a keyword such as constfrom an This is called stringizing . sprintf(char*, const char*, ) will fail on some versions of compilers when you pass a std::string to %s. How do I concatenate a string and an integer to make a filename? What is the term for a thing instantiated by saying it? We utilize asprintf function to store the passed integer as a character string. Description To concatenate multiple strings into a single string in Microsoft Excel, you can use the & operator to separate the string values. Why doesn't stringification and string-concatenation work? How to call a Variadic C function in Swift? Can renters take advantage of adverse possession under certain situations? Is there and science or consensus or theory about whether a black or a white visor is better for cycling? New framing occasionally makes loud popping sound when walking upstairs. Not the answer you're looking for? Sean 4984 score:26 @Koldsoar the quotes mean: the function is not part of the standard C library. Strings can simply be juxtaposed in C, and the compiler will concatenate them, which is what this macro does. rev2023.6.29.43520. If you have C++11, you can use std::to_string. Can one be Catholic while believing in the past Catholic Church, but not the present? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. My compiler is GCC 4.1 on CentOS 5. Is it usual and/or healthy for Ph.D. students to do part-time jobs outside academia? Famous papers published in annotated form? Macros with arguments Frozen core Stability Calculations in G09? Do spelling changes count as translations for citations when using different English dialects? I want the "LEDS" to be replaced by 48 within the string literal inside the asm() block below. 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. Not the answer you're looking for? What's the meaning (qualifications) of "machine" in GPL's "machine-readable source code"? Why would a god stop using an avatar's body? why does music become less harmonic if we transpose it down to the extreme low end of the piano? You misunderstand both my comment and the C language. Find centralized, trusted content and collaborate around the technologies you use most. Two or more substrings joining together to form a sentence or new strings are known as concatenation. Code: ? How to define string literal with character type that depends on template parameter? Does a constant Radon-Nikodym derivative imply the measures are multiples of each other? 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. Protein databank file chain, segment and residue number modifier. There are two concatenation operators, + and &. 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. I put the month end date 5 columns to the right for the time being and in the intention after deleting it after concatenation automatically. The solution should also work for MinGW. You don't need that sort of solution for string literals, since they are concatenated at the language level, and it wouldn't work anyway because "s""1" isn't a valid preprocessor token. Is it possible to get the value of a #defined integer symbol to be inserted verbatim into a string literal that is part of an assembly section in GCC (AVR Studio)? So I feel that it's best to just not use the macro at all. I decided not to mention for anonymous namespace. Other than heat. How could a language make the loop-and-a-half less error-prone? If the argument passed to. We can create two or more than two strings in macro, then simply write them one after another to convert them into a concatenated string. First turns str1 and str2 into strings (let's say "hello" and "world" if you use it like this space_conc(hello, world)) and places them next to each other with the simple, single-space, string inbetween. Magic? As a worksheet function, the & operator can be entered as part of a formula in a cell of a worksheet. note that snprintf is equally non-standard c++ (like itoa which you mention). For example, say we have two strings: "C programming" and "language". @tenfour sincerely I didn't know (as I'm not an expert of C++). There's no particular reason why the content of the string should be a valid C expression. And passing args to another macro function doesn't help, because string literals can't be pasted together -- "s""1" is not a valid token. rev2023.6.29.43520. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. before trying to compose anything complex with them. What was the symbol used for 'one thousand' in Ancient Rome? Protein databank file chain, segment and residue number modifier. Can't see empty trailer when backing down boat launch. TOKENPASTE uses. C preprocessor: stringification does not work. Edit: This is for a microcontroller firmware project - and just to make life interesting, there is almost no spare room for new code to be added. Unlike normal parameter replacement, the argument is not macro-expanded first. Macros are not functions even if sometimes they look similar. Making statements based on opinion; back them up with references or personal experience. Concatenation is the process of appending one string to the end of another string. How do I concatenate two string macros in C? Example #1 Here, the strings string_1 and string_2 get concatenated and the final result is stored in string_1. 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. 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. I couldn't say how many times I googled it and copied from this exact answer, but it's going to be in double digits. Well in my case I make sure my macro cannot clash with other names (macro names are prefixed) and I use them only for strings, which give the name to variable in my IO dll that is also used by other users. GDPR: Can a city request deletion of all personal data that uses a certain domain for logins? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is there a way to use DNS to block access to my domain? Raw concat.c #include <stdio.h> #define concat0 (str1, str2) (str1 " " str2) #define concat1 (str1, str2) (#str1 " " #str2) int main () { printf ("%s\n%s\n", concat0 ("a","b"), concat1 ("a","b")); return 0; } Sign up for free to join this conversation on GitHub . 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Creating C macro with ## and __LINE__ (token concatenation with positioning macro), Concatenate strings using preprocessor in C, concatenating nested strings using macros. 2. Find centralized, trusted content and collaborate around the technologies you use most. Learn more about Teams rev2023.6.29.43520. Allocating the memory "for you" is hardly doing you a favor. Does a simple syntax stack based language need a parser? 2. is slow as std::to_string(age) creates a temporary string that is appended to the result. Instead of macros, you can do this with inline function. I'm trying to figure out how I can concatenate a #define'd int to a #define'd string using the C Preprocessor. Unlike normal parameter replacement, the argument is not macro-expanded first. Using this function, we can concatenate two std::string objects (C++ style strings) as shown in the below example. Uber in Germany (esp. Counting Rows where values can be stored in multiple columns. You can use std::string for concatenation, though - it is one of the easiest solutions to this problem. Concatenate strings using preprocessor in C, concatenating nested strings using macros, variable strings concatenation in macro in C. Why is there a drink called = "hand-made lemon duck-feces fragrance"? Is there any particular reason to only include 3 out of the 6 trigonometry functions? 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, concatenating nested strings using macros. Why is there inconsistency about integral numbers of protons in NMR in the Clayden: Organic Chemistry 2nd ed.? Creating C macro: concatenate string and number. Function that creates a different csv file every time it is run, copy_to_user to pass datatype of int - object. And when I tried to do something like, For most use cases, using templates that tie either the left or the right operand to a string (which includes, You're commenting on a 12-year old answer. A preprocessor macro is text replacement at compile time. NOTE 2: the previous functions (get_classmate_path() and get_classmate_info_path()) may return NULL in case of errors. I thought I could do something like (the real function would have statements within the braces): Which I hoped would expand to something like: That doesn't work. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. But is there a direct way? Does the debt snowball outperform avalanche if you put the freed cash flow towards debt? Concatenating an int to a string or converting in C, Convert int to string and concatenate the result. Using, The difference is that your code crashes (or worse yet yields a privilege compromise) when somebody forgets to change the buffer size, while the version with. Spaced paragraphs vs indented paragraphs in academic textbooks. Note Now I have a set of #define'd switches and I want VERSION to reflect which of them are on. Already have an account? What you could do is to define a C function that does the concatenation and use this function in the macro definition. What is the earliest sci-fi work to reference the Titanic? Here is what I wrote so far which does not work. Hi @vitaut, how to make codes work with number: If I try to add to integers or an integer and a double, will this function be called ? There is a function I wrote, which takes the int number as the parameter, and convert it to a string literal. 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. Use sprintf (or snprintf if like me you can't count) with format string "pre_%d_suff". If you want to do this, I advise giving it a different name, like STRINGIZE_EXPR. Connect and share knowledge within a single location that is structured and easy to search. 3 Answers Sorted by: 49 Try this #define space_conc (str1,str2) #str1 " " #str2 The '##' is used to concatenate symbols, not strings. std::string s = "a" "b"; So I feel that it's best to just not use the macro at all. I swear I had to remove it on 20+ lines year ago in order to compile. Is there a way to use DNS to block access to my domain? Does a constant Radon-Nikodym derivative imply the measures are multiples of each other? Novel about a man who moves between timelines, Can't see empty trailer when backing down boat launch. Q&A for work. rev2023.6.29.43520. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. Connect and share knowledge within a single location that is structured and easy to search. Can't see empty trailer when backing down boat launch. It seems to me that the simplest answer is to use the sprintf function: Then your usage would look something like this. 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. Insert records of user Selected Object without knowing object first. Why it is called "BatchNorm" not "Batch Standardize"? Other than heat, A Chemical Formula for a fictional Room Temperature Superconductor. (simplified) So the result of your macro will be the string literal followed by the function name which is a syntax error. Can renters take advantage of adverse possession under certain situations? Cologne and Frankfurt). @CodyGray, stringification doesn't "evaluate" what you pass in, it simply takes the characters within the argument and dumps them straight out vrbatim unless you use an extra macro to substitute the desired characters before stringification. clobbering registers without telling it)? Strings can simply be juxtaposed in C, and the compiler will concatenate them, which is what this macro does. I will show it in two ways: Convert the number to string using to_string(i). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. I'd probably pick, QString("Something ") + QString::number(someIntVariable) also works, Note that this lambda would not be thread-safe / re-entrant, unlike some of the other solutions presented here. Managed C++ also has a Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Counting Rows where values can be stored in multiple columns, How to inform a co-worker about a lacking technical skill without sounding condescending. Famous papers published in annotated form? Was the phrase "The world is yours" used as an actual Pan American advertisement? Here's one way to make sure it works:
char buffer[128]; buffer[sizeof(buffer)-1] = '\0'; snprintf(buffer, sizeof(buffer)-1, "%s%d", name.c_str(), age); std::cout << buffer << std::endl;
. Spaced paragraphs vs indented paragraphs in academic textbooks. Cologne and Frankfurt). Connect and share knowledge within a single location that is structured and easy to search. and in the C language, separating two strings with space as in "s" "1" is exactly equivalent to having a single string "s1". (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.). Teen builds a spaceship and gets stuck on Mars; "Girl Next Door" uses his prototype to rescue him and also gets stuck on Mars, How to inform a co-worker about a lacking technical skill without sounding condescending. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. A more general solution is: Thanks for contributing an answer to Stack Overflow! The first "STR_HELPER" is required because '#' only works with a macro argument. Other posters suggested using itoa. Making statements based on opinion; back them up with references or personal experience. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Connect and share knowledge within a single location that is structured and easy to search. The problem with the second example appears to be circular logic. How can I handle a daughter who says she doesn't want to stay with me more than one day? What is the status for EIGHT piece endgame tablebases? Otherwise, add integer digit by digit to that string. Turns out this calls operator+=(char) and adds a non-printable character. Splendid. Do I owe my company "fair warning" about issues that won't be solved, before giving notice? Teams. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. How are we doing? I'm not at all familiar with the magic of inlining AVR assembly code into AVR Studio's GCC compiler. =CONCATENATE (E2,"-",F2) But the & operator always concatenates strings. How could a language make the loop-and-a-half less error-prone? How to concatenate two integers into one integer!! Was the phrase "The world is yours" used as an actual Pan American advertisement? @Wossname: How are you going to use "basic" asm (without constraints) without stepping on the compiler's toes (i.e. How is this not a duplicate? Difference between and in a sentence. What should be included in error messages. The solution should also work for MinGW. Making statements based on opinion; back them up with references or personal experience. rev2023.6.29.43520. 1. Let's see the example to concatenate two strings manually without using strcat () function. Continuing on the theme are these macros: Hint: The STRINGIZE macro above is cool, but if you make a mistake and its argument isn't a macro - you had a typo in the name, or forgot to #include the header file - then the compiler will happily put the purported macro name into the string with no error. 1960s? A working way is to write MY_FILE as a parametric macro: EDIT: As noted by "Lindydancer", this solution doesn't expand macros in arguments. Not the answer you're looking for? Can you please give more details on what could be the drawbacks on using it? STR() in this case will give a Narrow string. Shamelessly stolen from http://www.research.att.com/~bs/bs_faq2.html. A third approach would be to use sprintf or snprintf from the C library. Creating C macro with ## and __LINE__ (token concatenation with positioning macro). I have to combine the name( a char * variable) , number (an integer) , date(another char* variable) and send it as a string to the macro2 which will be called from the macro1. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, Keep in mind this is not necessarily dumb if you're doing something like, @R., of course the concept has uses, but it's generally connected to some other semantic value, or the option to replace the macro with something else (such as, for debugging purposes). 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. For completeness, the '##' operator in macro expansion is used like this, let's say you have, will result in the following if called as dumb_macro(hello, world). 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Format string in C++ when calling function, How to send command to Linux command from C program. Grappling and disarming - when and why (or why not)? Step 1: Go to Visual Basic Editor and create a VBA sub procedure. If you do this with macros, it will get too big and messy. Asking for help, clarification, or responding to other answers. It's Java-style pseudocode. This will tell you how to use snprintf, but I suggest a good C book! What is the earliest sci-fi work to reference the Titanic? Please use real code, and proper tagging, since tags is how people who can help find your question. How do you append an int to a string in C++? Not the answer you're looking for? 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. sequence of characters enclosed in double quotes. New framing occasionally makes loud popping sound when walking upstairs. rev2023.6.29.43520. Use the ##operator according to the following rules: Not the answer you're looking for? Why do CRT TVs need a HSYNC pulse in signal? rev2023.6.29.43520. The '##' is used to concatenate symbols, not strings. How do you build strings concatenated with int variables in C? It seems I can use any character I want besides space, for example: I want something to return "idan oop", suggestions?
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