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Search found 559 results on 23 pages for 'preprocessor abuse'.

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  • #if 0 as a define

    - by valerio
    I need a way to define a FLAGS_IF macro (or equivalent) such that FLAGS_IF(expression) <block_of_code> FLAGS_ENDIF when compiling in debug (e.g. with a specific compiler switch) compiles to if (MyFunction(expression)) { <block_of_code> } whereas in release does not result in any instruction, just as it was like this #if 0 <block_of_code> #endif In my ignorance on the matter of c/c++ preprocessors i can't think of any naive way (since #define FLAGS_IF(x) #if 0 does not even compile) of doing this, can you help? I need a solution that: Does not get messed up if */ is present inside <block_of_code> Is sure to generate 0 instructions in release even inside inline functions at any depth (i guess this excludes if (false){<block_of_code>} right?) Is standard compliant if possible Thank you

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  • How to keep g++ from taking header file from /usr/include?

    - by WilliamKF
    I am building using zlib.h which I have a local copy to v1.2.5, but in /usr/include/zlib.h there is v1.2.1.2. If I omit adding -I/my/path/to/zlib to my make I get error from using old version which doesn't have Z_FIXED: g++ -g -Werror -Wredundant-decls -D_FILE_OFFSET_BITS=64 -c -o ARCH.linux_26_i86/debug/sysParam.o sysParam.cpp sysParam.cpp: In member function `std::string CSysParamAccess::getCompressionStrategyName() const': sysParam.cpp:1816: error: `Z_FIXED' was not declared in this scope sysParam.cpp: In member function `bool CSysParamAccess::setCompressionStrategy(const std::string&, paramSource)': sysParam.cpp:1849: error: `Z_FIXED' was not declared in this scope Alternatively, if I add the include path to the zlib z1.2.5 I am using, I get double defines, it seems as if the zlib.h is included twice with two different sets of -D values, but I don't see how that is happening: g++ -g -Werror -Wredundant-decls -I../../src/zlib-1.2.5 -D_FILE_OFFSET_BITS=64 -c -o ARCH.linux_26_i86/debug/sysParam.o sysParam.cpp In file included from sysParam.cpp:24: ../../src/zlib-1.2.5/zlib.h:1582: warning: redundant redeclaration of `void* gzopen64(const char*, const char*)' in same scope ../../src/zlib-1.2.5/zlib.h:1566: warning: previous declaration of `void* gzopen64(const char*, const char*)' ../../src/zlib-1.2.5/zlib.h:1583: warning: redundant redeclaration of `long long int gzseek64(void*, long long int, int)' in same scope ../../src/zlib-1.2.5/zlib.h:1567: warning: previous declaration of `off64_t gzseek64(void*, off64_t, int)' ../../src/zlib-1.2.5/zlib.h:1584: warning: redundant redeclaration of `long long int gztell64(void*)' in same scope ../../src/zlib-1.2.5/zlib.h:1568: warning: previous declaration of `off64_t gztell64(void*)' ../../src/zlib-1.2.5/zlib.h:1585: warning: redundant redeclaration of `long long int gzoffset64(void*)' in same scope ../../src/zlib-1.2.5/zlib.h:1569: warning: previous declaration of `off64_t gzoffset64(void*)' ../../src/zlib-1.2.5/zlib.h:1586: warning: redundant redeclaration of `uLong adler32_combine64(uLong, uLong, long long int)' in same scope ../../src/zlib-1.2.5/zlib.h:1570: warning: previous declaration of `uLong adler32_combine64(uLong, uLong, off64_t)' ../../src/zlib-1.2.5/zlib.h:1587: warning: redundant redeclaration of `uLong crc32_combine64(uLong, uLong, long long int)' in same scope ../../src/zlib-1.2.5/zlib.h:1571: warning: previous declaration of `uLong crc32_combine64(uLong, uLong, off64_t)' Here some of the relavent lines from zlib.h referred to above: // This would be line 1558 of zlib.h /* provide 64-bit offset functions if _LARGEFILE64_SOURCE defined, and/or * change the regular functions to 64 bits if _FILE_OFFSET_BITS is 64 (if * both are true, the application gets the *64 functions, and the regular * functions are changed to 64 bits) -- in case these are set on systems * without large file support, _LFS64_LARGEFILE must also be true */ #if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *)); ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int)); ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile)); ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile)); ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t)); ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t)); #endif #if !defined(ZLIB_INTERNAL) && _FILE_OFFSET_BITS-0 == 64 && _LFS64_LARGEFILE-0 # define gzopen gzopen64 # define gzseek gzseek64 # define gztell gztell64 # define gzoffset gzoffset64 # define adler32_combine adler32_combine64 # define crc32_combine crc32_combine64 # ifdef _LARGEFILE64_SOURCE ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *)); ZEXTERN z_off_t ZEXPORT gzseek64 OF((gzFile, z_off_t, int)); ZEXTERN z_off_t ZEXPORT gztell64 OF((gzFile)); ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile)); ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t)); ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t)); # endif #else ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *)); ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int)); ZEXTERN z_off_t ZEXPORT gztell OF((gzFile)); ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile)); ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t)); ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t)); #endif // This would be line 1597 of zlib.h I'm not sure how to track this down further. I tried moving the include of zlib.h to the top and bottom of the includes list of the cpp file, but it made no difference. An excerpt of passing -E to g++ shows in part: extern int inflateInit2_ (z_streamp strm, int windowBits, const char *version, int stream_size); extern int inflateBackInit_ (z_streamp strm, int windowBits, unsigned char *window, const char *version, int stream_size); # 1566 "../../src/zlib-1.2.5/zlib.h" extern gzFile gzopen64 (const char *, const char *); extern off64_t gzseek64 (gzFile, off64_t, int); extern off64_t gztell64 (gzFile); extern off64_t gzoffset64 (gzFile); extern uLong adler32_combine64 (uLong, uLong, off64_t); extern uLong crc32_combine64 (uLong, uLong, off64_t); # 1582 "../../src/zlib-1.2.5/zlib.h" extern gzFile gzopen64 (const char *, const char *); extern long long gzseek64 (gzFile, long long, int); extern long long gztell64 (gzFile); extern long long gzoffset64 (gzFile); extern uLong adler32_combine64 (uLong, uLong, long long); extern uLong crc32_combine64 (uLong, uLong, long long); # 1600 "../../src/zlib-1.2.5/zlib.h" struct internal_state {int dummy;}; Not sure why lines 1566 and 1582 are coming out together in the CPP output, but hence the warning about duplicate declarations.

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  • C++ classes with members referencing each other

    - by Saad Imran.
    I'm trying to write 2 classes with members that reference each other. I'm not sure if I'm doing something wrong or it's just not possible. Can anyone help me out here... Source.cpp #include "Headers.h" using namespace std; void main() { Network* network = new Network(); system("pause"); return; } Headers.h #ifndef Headers_h #define Headers_h #include <iostream> #include <vector> #include "Network.h" #include "Router.h" #endif Network.h #include "Headers.h" class Network { protected: vector<Router> Routers; }; Router.h #include "Headers.h" class Router { protected: Network* network; public: }; The errors I'm getting are: error C2143: syntax error : missing ';' before '<' error C2238: unexpected token(s) preceding ';' error C4430: missing type specifier - int assumed. I'm pretty sure I'm not missing any semicolons or stuff like that. The program works find if I take out one of the members. I tried finding similar questions and the solution was to use pointers, but that's what I'm doing and it does't seem to be working!

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  • Linker, Libraries & Directories Information

    - by m00st
    I've finished both my C++ 1/2 classes and we did not cover anything on Linking to libraries or adding additional libraries to C++ code. I've been having a hay-day trying to figure this out; I've been unable to find basic information linking to objects. Initially I thought the problem was the IDE (Netbeans; and Code::Blocks). However I've been unable to get wxWidgets and GTKMM setup. Can someone point me in the right direction on the terminology and basic information about #including files and linking files in a Cpp application? Basically I want/need to know everything in regards to this process. The difference between .dll, .lib, .o, .lib.a, .dll.a. The difference between a .h and a "library" (.dll, .lib correct?) I understand I need to read the compiler documentation I am using; however all compilers (that I know of) use linker and headers; I need to learn this information. Please point me in the right direction! :] So far on my quest I've found out: Linker links libraries already compiled to your project. .a files are static libraries (.lib in windows) .dll in windows is a shared library (.so in *nix) Thanks

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  • How do I inhibit "note C6311" in Microsoft C compiler?

    - by piCookie
    In this maximally clipped source example, the manifest constant FOOBAR is being redefined. This is deliberate, and there is extra code in the live case to make use of each definition. The pragma was added to get rid of a warning message, but then a note appeared, and I don't seem to find a way to get rid of the note. I've been able to modify this particular source to #undef between the #define, but I would like to know if there's a way to inhibit the note without requiring #undef, since there are multiple constants being handled the same way. #pragma warning( disable : 4005 ) // 'identifier' : macro redefinition #define FOOBAR FOO #define FOOBAR BAR The compiler banner and output are as follows Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 Copyright (C) Microsoft Corp 1984-1998. All rights reserved. message.c message.c(3) : note C6311: message.c(2) : see previous definition of 'FOOBAR'

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  • Determining whether compiling on Windows or other system

    - by NumberFour
    Hi, Im currently developing a cross-platform C application. Is there any compiler macro which is defined only during compilation on Windows, so I can #ifdef some Windows specific #includes? Typical example is selecting between WinSock and Berkeley sockets headers: #ifdef _WINDOWS #include <winsock.h> #else #include <sys/socket.h> #include <netinet/in.h> #include <sys/un.h> #include <arpa/inet.h> #include <netdb.h> #endif So the thing Im looking for is something like that _WINDOWS macro. Thanks for any tips.

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  • Why I get errors when I try to out a compiler defined macro using a pragma message?

    - by bogdan
    I would like to know why the Visual C++ compiler gets me an warning/error if I use the following code: #pragma message( "You have " _MSC_FULL_VER ) Here is what I get: error C2220: warning treated as error - no 'object' file generated warning C4081: expected ':'; found ')' The problem reproduces for _MSC_FULL_VER or _MSV_VER but not if I try to use others like __FILE__ or __DATE__. These macros are defined, they are documented on msdn

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  • c++ variadic macro argument count

    - by chedi
    Hi, is there any way to count the number of argument of a variadic macro, other than this one: #define PP_NARG(...) PP_NARG_(__VA_ARGS__,PP_RSEQ_N()) #define PP_NARG_(...) PP_ARG_N(__VA_ARGS__) #define PP_ARG_N( \ _1, _2, _3, _4, _5, _6, _7, _8, _9,_10, _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \ _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \ _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \ _61,_62,_63,N,...) N #define PP_RSEQ_N() \ 63,62,61,60,59,58,57,56,55,54,53,52,51,50,49,48,47,46,45,44,43,42,41,40, \ 39,38,37,36,35,34,33,32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16, \ 15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0

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  • Looking for a good explanation of the table generation macro idiom

    - by detly
    I want to make this clear up front : I know how this trick works, what I want is a link to a clear explanation to share with others. One of the answers to a C macro question talks about the "X macro" or "not yet defined macro" idiom. This involves defining something like: #define MAGIC_LIST \ X(name_1, default_1) \ X(name_2, default_2) \ ... Then to create, say, an array of values with named indices you do: typedef enum { #define X(name, val) name, MAGIC_LIST #undef X } NamedDefaults; You can repeat the procedure with a different #define for X() to create an array of values, and maybe debugging strings, etc. I'd like a link to a clear explanation of how this works, pitched at someone who is passably familiar with C. I have no idea what everyone usually calls this pattern, though, so my attempts to search the web for it have failed thus far. (If there is such an explanation on SO, that'd be fine...)

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  • (Cpp) Linker, Libraries & Directories Information

    - by m00st
    I've finished both my C++ 1/2 classes and we did not cover anything on Linking to libraries or adding additional libraries to C++ code. I've been having a hay-day trying to figure this out; I've been unable to find basic information linking to objects. Initially I thought the problem was the IDE (Netbeans; and Code::Blocks). However I've been unable to get wxWidgets and GTKMM setup. Can someone point me in the right direction on the terminology and basic information about #including files and linking files in a Cpp application? Basically I want/need to know everything in regards to this process. The difference between .dll, .lib, .o, .lib.a, .dll.a. The difference between a .h and a "library" (.dll, .lib correct?) I understand I need to read the compiler documentation I am using; however all compilers (that I know of) use linker and headers; I need to learn this information. Please point me in the right direction! :] Thanks

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  • #include in C# (conditional compilation)

    - by HeavyWave
    Is it possible in C# to set such a condition that if the condition is true - compile one file;If condition is false - compile another file? Sort of like #ifdef DEBUG #include Class1.cs #else #include Class2.cs #endif Or possibly set it up in project properties.

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  • Help with data retrieval MACRO

    - by Andrei Ciobanu
    Hello, given the following structure: struct nmslist_elem_s { nmptr data; struct nmslist_elem_s *next; }; typedef struct nmslist_elem_s nmslist_elem; Where: typedef void* nmptr; Is it possible to write a MACRO that retrieves the data from the element and cast it to the right type: MACRO(type, element) that expands to *((type*)element->data). For example for int, i would need something like this: *((int*)(element->data)) .

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  • How to prevent duplicates, macro or something?

    - by blez
    Well, the problem is that I've got a lot of code like this for each event passed to the GUI, how can I shortify this? Macros wont do the work I guess. Is there a more generic way to do something like a 'template' ? private delegate void DownloadProgressDelegate(object sender, DownloaderProgressArgs e); void DownloadProgress(object sender, DownloaderProgressArgs e) { if (this.InvokeRequired) { this.BeginInvoke(new DownloadProgressDelegate(DownloadProgress), new object[] { sender, e }); return; } label2.Text = d.speedOutput.ToString(); } private delegate void DownloadSpeedDelegate(object sender, DownloaderProgressArgs e); void DownloadSpeed(object sender, DownloaderProgressArgs e) { if (this.InvokeRequired) { this.BeginInvoke(new DownloadSpeedDelegate(DownloadSpeed), new object[] { sender, e }); return; } string speed = ""; speed = (e.DownloadSpeed / 1024).ToString() + "kb/s"; label3.Text = speed; }

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  • How to inline a function for only release build.

    - by Benjamin
    // common.h // This is foo funtion. It has a body. __inline void foo() { /* something */ } // a.cpp #include "common.h" // for foo function // Call foo // b.cpp #include "common.h" // for foo function // Call foo I would like to inline the foo function only when I build for release. -I dont want to inline functions for Debug build. I tried it but linker errors annoyed me. In this case, foo function's body is defined in common.h header file. so if I just do //common.h #if !defined(_DEBUG) __inline #endif void foo() { /* something */ } I will be met a link error in DEBUG build. Because two modules try to include common.h. I have no idea to solve it. Is it possible?

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  • What's the C strategy to "imitate" a C++ template ?

    - by Andrei Ciobanu
    After reading some examples on stackoverflow, and following some of the answers for my previous questions (1), I've eventually come with a "strategy" for this. I've come to this: 1) Have a declare section in the .h file. Here I will define the data-structure, and the accesing interface. Eg.: /** * LIST DECLARATION. (DOUBLE LINKED LIST) */ #define NM_TEMPLATE_DECLARE_LIST(type) \ typedef struct nm_list_elem_##type##_s { \ type data; \ struct nm_list_elem_##type##_s *next; \ struct nm_list_elem_##type##_s *prev; \ } nm_list_elem_##type ; \ typedef struct nm_list_##type##_s { \ unsigned int size; \ nm_list_elem_##type *head; \ nm_list_elem_##type *tail; \ int (*cmp)(const type e1, const type e2); \ } nm_list_##type ; \ \ nm_list_##type *nm_list_new_##type##_(int (*cmp)(const type e1, \ const type e2)); \ \ (...other functions ...) 2) Wrap the functions in the interface inside MACROS: /** * LIST INTERFACE */ #define nm_list(type) \ nm_list_##type #define nm_list_elem(type) \ nm_list_elem_##type #define nm_list_new(type,cmp) \ nm_list_new_##type##_(cmp) #define nm_list_delete(type, list, dst) \ nm_list_delete_##type##_(list, dst) #define nm_list_ins_next(type,list, elem, data) \ nm_list_ins_next_##type##_(list, elem, data) (...others...) 3) Implement the functions: /** * LIST FUNCTION DEFINITIONS */ #define NM_TEMPLATE_DEFINE_LIST(type) \ nm_list_##type *nm_list_new_##type##_(int (*cmp)(const type e1, \ const type e2)) \ {\ nm_list_##type *list = NULL; \ list = nm_alloc(sizeof(*list)); \ list->size = 0; \ list->head = NULL; \ list->tail = NULL; \ list->cmp = cmp; \ }\ void nm_list_delete_##type##_(nm_list_##type *list, \ void (*destructor)(nm_list_elem_##type elem)) \ { \ type data; \ while(nm_list_size(list)){ \ data = nm_list_rem_##type(list, tail); \ if(destructor){ \ destructor(data); \ } \ } \ nm_free(list); \ } \ (...others...) In order to use those constructs, I have to create two files (let's call them templates.c and templates.h) . In templates.h I will have to NM_TEMPLATE_DECLARE_LIST(int), NM_TEMPLATE_DECLARE_LIST(double) , while in templates.c I will need to NM_TEMPLATE_DEFINE_LIST(int) , NM_TEMPLATE_DEFINE_LIST(double) , in order to have the code behind a list of ints, doubles and so on, generated. By following this strategy I will have to keep all my "template" declarations in two files, and in the same time, I will need to include templates.h whenever I need the data structures. It's a very "centralized" solution. Do you know other strategy in order to "imitate" (at some point) templates in C++ ? Do you know a way to improve this strategy, in order to keep things in more decentralized manner, so that I won't need the two files: templates.c and templates.h ?

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  • C++ conditional compilation

    - by Shaown
    I have the following code snippet #ifdef DO_LOG #define log(p) record(p) #else #define log(p) #endif void record(char *data){ ..... ..... } Now if I call log("hello world") in my code and DO_LOG isn't defined, will the line be compiled, in other words will it eat up the memory for the string "hello world"? P.S. There are a lot of record calls in the program and it is memory sensitive, so is there any other way to conditionally compile so that it only depends on the #define DO_LOG? Thanks in advance.

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  • C/C++ line number

    - by Betamoo
    In the sake of debugging purposes, can I get the line number in C/C++ compilers? (standard way or specific ways for certain compilers) e.g if(!Logical) printf("Not logical value at line number %d \n",LineNumber); // How to get LineNumber without writing it by my hand?(dynamic compilation) Thanks

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  • SASS mixin for swapping images / floats on site language (change)

    - by DBUK
    Currently using SASS on a website build. It is my first project using it, tried a little LESS before and liked it. I made a few basic mixins and variables with LESS, super useful stuff! I am trying to get my head around SASS mixins, and syntax, specifically for swapping images when the page changes to a different language, be that with body ID changing or <html lang="en">. And, swapping floats around if, for example, a website changed to chinese. So a mixin where float left is float left unless language is AR and then it becomes float right. With LESS I think it would be something like: .headerBg() when (@lang = en) {background-image:url(../img/hello.png);} .headerBg() when (@lang = it) {background-image:url(../img/ciao.png);} .header {.headerBg(); width: 200px; height:100px} .floatleft() when (@lang = en) { float: left;} .floatleft() when (@lang = ar) { float: right;} .logo {.floatleft();} Its the syntax I am having problems with combined with a brain melting day.

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  • Why the output for "a" is -80?

    - by Abhi
    #include<stdio.h> #include<conio.h> #define ABC 20 #define XYZ 10 #define XXX ABC - XYZ void main() { int a; a = XXX * 10; printf("\n %d \n", a); getch(); } I thought the output should be 100 but when i saw the result i found o/p as -80. when i put bracket as #define XXX (ABC-XYZ) then i get output as 100 but without bracket i get o/p as -80.

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  • Returning pointer to a certain value in a macro?

    - by Andrei Ciobanu
    Is it possible to write a macro that has a type and a value as its input parameters (MACRO(type,value)), and returns a valid pointer to a location that holds the submitted value. This macro should perform like the following function, but in a more generic manner: int *val_to_ptr(int val){ int *r = NULL; r = nm_malloc(sizeof(*r)); *r = val; return r; } Where nm_malloc() is a failsafe malloc. The Macro usage should be compatible with this usage: printf("%d",*MACRO(int,5)); Is it possible to achieve that ?

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  • C++: Can a macro expand "abc" into 'a', 'b', 'c'?

    - by Peter Alexander
    I've written a variadic template that accepts a variable number of char parameters, i.e. template <char... Chars> struct Foo; I was just wondering if there were any macro tricks that would allow me to instantiate this with syntax similar to the following: Foo<"abc"> or Foo<SOME_MACRO("abc")> or Foo<SOME_MACRO(abc)> etc. Basically, anything that stops you from having to write the characters individually, like so Foo<'a', 'b', 'c'> This isn't a big issue for me as it's just for a toy program, but I thought I'd ask anyway.

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