You may encounter an error pointing to the c preprocessor error directive. It turns out that there are several ways to solve this problem, so we’ll look at them now.
The #error directive prints a custom error message at compile time and then finishes our compilation.
Syntax
What are the correct preprocessor directives in C?
# Error token string
The error message sent by this directive contains a token string parameter. The token string parameter simply cannot undergo macro expansion. Directive This is very useful during preprocessing to notify the developer of a program inconsistency or constraint violation. The following example shows preprocessing error handling:
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# if in progress! defined (__ cplusplus)#error Requires a C ++ compiler.#end if
The “ #error ” directive causes the preprocessor to report a fatal error.Guilt. Tokens that make up the rest of the “ #error ” stringare used below as the corresponding error message.
You must use “ #error ” in the condition foundParameter combination You know the program does not followSupport. For example, if you know that a program does not normally docorrectly on a suitable VAX you can write
If you have enough configuration settings, do so. need to tweaksequential installation, you can use conditions to detectinconsistency and report it with “ #error “. Example,
What is preprocessor error in C?
The “ #warning ” directive is similar to the “ #error ” directive, but it callsA preprocessor for creating the index and continuing preprocessing. “ #warning ” TokensThe following is almost always used as a warning message.
You can use “ #warning ” in legacy message header files.Redirect the user to the h2 tag file which should be used instead.
No #error ‘none of the macros extend #warning ‘ their argument.Samples of the interior space have been replaced by a single space.The string mustIt can be filled in with markers. It’s smarter thanThe argument to these directives is a string constant equal to one hour; who avoidsProblems with apostrophes and how.
#ifdef __vax__#error “Doesn’t work with VAXen. See get_last_object for comments.”#end if
#if! defined (FOO) && defined (BAR)#error "BAR must have FOO."#end if
What is the #error statement in C? What does the perk have to do with it?
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requested on March 16, 2011 at 5:59 am
The preprocessor error directive causes the preprocessor to generate an error message and cannot compile it. For example, #error statements in the source file can prevent marketers from generating if a section of a tutorial has been reached and should be skipped.
Isn’t This The Method You Are Looking For? Check Out The Other Questions Called C C-preprocessor Or Ask Your Final Question.
This is an important preprocessor directive that is used (for example) before waiting for one of the many future characters -D to be defined, but practically not.
#if defined (BUILD_TYPE_NORMAL)# DEBUG (x) defines do; not forgetting (0) / * zero paranoid code * /#elif defined (BUILD_TYPE_DEBUG)# DEBUG (x) create _debug_trace x / * e.g. DEBUG ((_ debug_trace args)) * /#another# error "Please enter build type in Makefile"#end if
If the preprocessor encounters you, the #error it directive will report the series as an error message and complete compilation; The exact form of the error message depends on the compiler.
Reply 16, Mar 11 @ 6:09 am
The ‘#error’ directive causes the real preprocessor to report a serious error. The error message is the bridal shower, which is the rest of the line that uses ‘#error’. You cannot use #warning ‘on legacy header files followed by a message directing the user to a specific header file to be included instead.
#if named USING_SQLITE && defines USING_MYSQL#error You cannot use SQLite and MySQL at the same time#end if#if! (defines USING_SQLITE && defines USING_MYSQL)#error You must use either sqlite or mysql#end if#ifdef USING_SQLITE// ...#end if#ifdef USING_MYSQL// ...#end if
answered Mar 16 ’11 at 6:15 am
If the compiler regularly compiles this line, it displays a fatal compiler error: and also stops the program from continuing to compile:
#include #ifndef __MATH_H#error First include and then compile#anotherint main () go a, b = 25; a = square (b); printf ("% f", a); Return 0;#end ifOutput: compiler error -> Error directive: enable first, then compile
answered Jan 14 at 8:18 am
Description. In the C programming language, the new #error directive causes preprocessing to stop at our point where the directive is encountered. Information is printed after the #error directive indicating that the message will be generated before preprocessing stops.
