#elif with no expression

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August undefined, 2024

WebJan 24, 2024 · When there's no #else clause, and all instances of constant-expression in the #if block are false, no text block is selected. The constant-expression is an integer … WebJul 2, 2016 · The == operator in preprocessor expressions doesn't compare strings or identifiers, it only compares integer expressions. You can do what you're trying to do by defining integer values for A, B, and myvar, for example: #define A 1 #define B 2 #define myvar B #if myvar == A cout << "A" << endl; #elif myvar == B cout << "B" << endl; #else …

C++ #if #elif #endif don

WebThe preprocessor directive which checks whether a constant expression results in a zero or non-zero value _____ a) #if b) #ifdef c) #undef d) #ifndef View Answer. ... Since the condition given for #elif is true, the value stored in ‘q’ will be printed, that is 15. Sanfoundry Global Education & Learning Series – C Programming Language. ... rafting huesca

[Solved] What does "#elif with no expression" mean?

Web'-elif-' If the constant expression evaluates to a nonzero value, the lines of code that immediately follow the condition are passed on to the compiler. If the expression … WebMar 2, 2024 · #if, #elif The expression may contain: unary operators in form defined identifier or defined (identifier). The result is 1 if the identifier was defined as a macro name, otherwise the result is 0 . (since C++17) __has_include expressions, which detects whether a header or source file exists. WebMay 5, 2024 · Yes, I want it to process that line like an #ifdef, per the instructional text quoted above and repeated here: If an #ifdef is evaluated to be false, then the #elseif … rafting hiwassee river

C preprocessor directives – #include, #define, #undef

boost/log/detail/config.hpp - 1.82.0

WebMar 3, 2013 · 1 Answer Sorted by: 24 Because #elif expects an expression, just like #if. You want to use #else. Otherwise you have to give the expression: #ifndef L #define L 152064 /* (352 * 288 * 1.5) */ #elif defined (L) #error "L defined elsewhere" #endif … Web#elif是#else和#if的缩写，不是#else和 #ifdef，所以你的行应该是: #elif defined(SSVU_OS_WINDOWS) 编辑:因为未定义的宏在 #if 表达式中扩展为 0，您还可以 … rafting hronWebThis directive delimits alternative source lines to be compiled if the constant expression in the corresponding #if, #ifdef, #ifndef, or another #elif directive is false and if the … rafting icon

"Web因为 #elif 需要一个表达式，就像 #if 一样。你想使用 #else。否则你必须给出表达式: #ifndef L #define L 152064 /* (352 * 288 * 1.5) */ #elif defined(L) #error "L defined elsewhere" … " - #elif with no expression

#elif with no expression

Webboost/log/detail/config.hpp /* * Copyright Andrey Semashev 2007 - 2015. * Distributed under the Boost Software License, Version 1.0. WebAug 23, 2024 · You can use any number of #elif directives in a conditional block. syntax. #elif constant-expression. constant-expression. Expression to be checked. This value …

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WebSolution : This error is because #elif also expected the expression check as we have done with #ifdef. hence, when we change below line of code #elif … WebJul 8, 2024 · I think you may have this conditional to keep old code in the elif around, is so this change may work:

WebNov 18, 2024 · We use #include directive to include contents of another file (especially header file’s) to a program. We can include a file in two different ways. #include . This variant of including header file, searches header file … WebMay 5, 2024 · c:\users\admin\appdata\local\temp\arduino_build_403913\sketch\configuration.h:159:6: …

WebSep 15, 2009 · And #if requires an expression, which is missing if the > macro isn't defined. Rolf makes a good point, but a better solution is to use the improved preprocessor … WebJul 8, 2024 · I think you may have this conditional to keep old code in the elif around, is so this change may work:

WebNov 26, 2024 · 1、如果你用gcc -E hello.c -o hello.i 编译，（预编译命令）会出现：error: #if with no expression的错误。原因是BB虽然定义了，但是定义的是空值，放在#elif后面 …

WebSep 15, 2009 · 1. #elif WITHB //<-- ERROR: #if with no expression. This expression equals to. 1. #else if WITHB == TRUE //<-- ERROR: #if with no expression. but since you only defined WITHB (without a value) it is expanded to 0, which equals FALSE. Try either to define WITHB with a value or change your if-statement as follows: 1. rafting historyWebIf expression evaluates to False, each expression-n (if any) is evaluated in turn. When expression-n evaluates to True, the statements following the associated #elif directive are executed. If no expression-n evaluates to True, or there are no #elif directives, the statements following the #else directive, are executed. rafting horseshoe bend azWebThe #elif directive evaluates its condition only when the original condition on the #if evaluates to false and all conditions associated with preceding #elif ... This operator can … rafting holidaysWebOct 31, 2024 · #ifdef __linux__ #elif defined (_WIN32) #endif Which is probably not obvious to everyone. Using Kerrick SB 's answer, you can also write the same #if statement as: #if defined (__linux__) #elif defined (_WIN32) #endif rafting illustrationWeb4.2.3 Defined . The special operator defined is used in `#if' and `#elif' expressions to test whether a certain name is defined as a macro.defined name and defined (name) are both expressions whose value is 1 if name is defined as a macro at the current point in the program, and 0 otherwise. Thus, #if defined MACRO is precisely equivalent to #ifdef … rafting in bozeman mtWebOct 12, 2024 · The controlling expression should be essentially boolean type. The result of the equality, relational etc operators is to be regarded as essentially boolean, whereas showing in an int or pointer without an operator means that the expression is … rafting icelandWebSep 10, 2024 · The text was updated successfully, but these errors were encountered: rafting in cherokee nc