Error directive

C++

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Named requirements

Language support library

Concepts library (C++20)

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Regular expressions library (C++11)

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Technical Specifications

C++ language

General topics
Preprocessor Comments	Keywords Escape sequences
Flow control
Conditional execution statements
if	switch
Iteration statements (loops)
for range-for (C++11)	while do-while
Jump statements
continue - break	goto - return
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Function declaration
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inline specifier
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noexcept specifier (C++11)
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throw-expression	try-catch block
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decltype (C++11) auto (C++11) alignas (C++11)	const/volatile constexpr (C++11)
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Expressions
Value categories Order of evaluation	Operators Operator precedence
Alternative representations
Literals
Boolean - Integer - Floating-point
Character - String - nullptr (C++11)
User-defined (C++11)
Utilities
Attributes (C++11)
Types
typedef declaration
Type alias declaration (C++11)
Casts
Implicit conversions - Explicit conversions
static_cast - dynamic_cast
const_cast - reinterpret_cast
Memory allocation
new expression	delete expression
Classes
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Virtual function override specifier (C++11) final specifier (C++11)	explicit (C++11) static
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Templates
Class template Function template	Template specialization Parameter packs (C++11)
Miscellaneous
Inline assembly	History of C++

Preprocessor

#if#ifdef#ifndef#else#elif#endif

#define#undef#,## operators

#include__has_include(C++17)

#error

#pragma_Pragma(C++11)

#line

Shows the given error message and renders the program ill-formed.

Syntax

#error error_message

Explanation

After encountering the #error directive, an implementation displays the diagnostic message error_message and renders the program ill-formed (the compilation stops).

error_message can consist of several words not necessarily in quotes.