C++ reserves a set of words for use within the language as keywords. Keywords may not be used as program identifiers. Table 1 below lists the complete set of C++ keywords.

Table 1: C++ Keywords

asm

do

if

return

try

auto

double

inline

short

typedef

bool

dynamic_cast

int

signed

typeid

break

else

long

sizeof

typename

case

enum

mutable

static

union

catch

explicit

namespace

static_cast

unsigned

char

export

new

struct

using

class

extern

operator

switch

virtual

const

false

private

template

void

const_cast

float

protected

this

volatile

continue

for

public

throw

wchar_t

default

friend

register

true

while

delete

goto

reinterpret_cast

    
 

C++ also reserves a number of words that can be used as alternative names for various operators. These alternative names are provided to support character sets that do not support the standard set of C++ operator symbols. These names, listed in Table 2 below, also may not be used as identifiers:

 

Table 2: C++ Operator Alternative Names

and

bitand

compl

not_eq

or_eq

xor_eq

and_eq

bitor

not

or

xor

  

In addition to the keywords, the standard also reserves a set of identifiers for use in the library. Identifiers cannot contain two consecutive underscores, nor can an identifier begin with an underscore followed immediately by an upper-case letter. Certain identifiers those that are defined outside a function may not begin with an underscore.