Are all of the features of C99 also in C++?

Question

This page lists 53 features that were new in C99 (i.e they are in C99 but not C89). Are all of these features also in C++? Even C++98?

If not, which of the features are in C++ and which are not?

Answer 1

The following C99 (ISO 9899:1999) features are fully supported by C++ (ISO 14882:2017):
(though library headers will be <cname> rather than <name.h>:

• wide character library support in <wchar.h> and <wctype.h> (originally specified in ISO/IEC 9899:1990/Amd.1:1995)
• type-generic math macros in <tgmath.h>
• the long long int type and library functions
• extended integer types
• increased minimum translation limits
• additional floating-point characteristics in <float.h>
• remove implicit int
• reliable integer division
• universal character names (\u and \U)
• extended identifiers
• hexadecimal floating-point constants and %a and %A printf/scanf conversion specifiers
• // comments
• specified width integer types and corresponding library functions in <inttypes.h> and <stdint.h>
• remove implicit function declaration
• preprocessor arithmetic done in intmax_t/uintmax_t
• mixed declarations and statements
• new block scopes for selection and iteration statements
• integer constant type rules
• integer promotion rules
• the vscanf family of functions in <stdio.h> and <wchar.h>
• additional math library functions in <math.h>
• treatment of error conditions by math library functions (math_errhandling)
• floating-point environment access in <fenv.h>
• IEC 60559 (also known as IEC 559 or IEEE arithmetic) support
• trailing comma allowed in enum declaration
• %lf conversion specifier allowed in printf
• inline functions
• the snprintf family of functions in <stdio.h>
• idempotent type qualifiers
• empty macro arguments
• additional predefined macro names
• _Pragma preprocessing operator
• standard pragmas
• __func__ predefined identifier
• va_copy macro
• additional strftime conversion specifiers
• LIA compatibility annex
• deprecate ungetc at the beginning of a binary file
• remove deprecation of aliased array parameters
• conversion of array to pointer not limited to lvalues
• relaxed constraints on aggregate and union initialization
• relaxed restrictions on portable header names
• return without expression not permitted in function that returns a value (and vice versa)
• macros with a variable number of arguments

The following C99 features have similar use in C++, but there are implementation differences and the languages are not code compatible:

• restricted character set support via digraphs and <iso646.h> (originally specified in ISO/IEC 9899:1990/Amd.1:1995)
• more precise aliasing rules via effective type
• complex (and imaginary) support in <complex.h>
• boolean type in <stdbool.h>
• new structure type compatibility rules (tag compatibility)

The following C99 features are not supported by C++:

• restricted pointers
• variable length arrays
• flexible array members
• static and type qualifiers in parameter array declarators
• compound literals
• designated initializers

Answer 2

Flexible array members are not part of any C++ standard (and the dynarray proposal was not adapted in C++). And there are many other less used C99 features which are not in C++.