Keywords, Directives

The C and C++ languages specify a few names that act as so-called keywords. They have a meaning that is firmly anchored in the language and may not be used, for example, as a name for a variable. Keywords help the programmer to write source code with more or less meaningful english expressions instead of cryptic characters.

Directive names are also listed on this page. Directives are names of preprocessor commands, which usually appear with a leading hash # character. More detailed information can be looked up in the preprocessor section.

asm

Keyword for directly entering assembly code.

#assert

Preprocessor directive for defining predicates.

attribute

Keyword for specifying attributes.

auto

Storage class for automatic Allokation and Deallokation.

break

Termination of the current loop or case distinction.

case

Defines a label for a case distinction.

char

Declaration with a byte sized integer type.

const

Qualifier for immutable structures.

continue

Statement for continuing the current loop.

default

Remaining label of a case distinction.

#define

Preprocessor directive for defining macros.

defined

Preprocessor operator for checking macro existance.

do

Initiates a do–while loop.

double

Declaration with a double floating point type.

else

Else part of an if structure.

#else

Else part of a conditional compilation.

#elif

Consecutive condition of a conditional compilation.

#endif

End of a conditional compilation.

enum

Declaration with an enumeration type.

#error

Output compiler error.

extern

Storage class for symbols defined elsewhere.

float

Declaration with a float floating point type.

for

Initiates a for loop.

goto

Statement for a jump to a label.

#ident

Preprocessor directive for an identification.

if

Initiates an if structure.

#if

Initiates a conditional compilation.

#ifdef

Conditional compilation when a macro exists.

#ifndef

Conditional compilation when a macro doesn't exists.

#include

Include files.

#include_next

Include files from the second directory.

inline

Compiler hint for directly injecting function code.

int

Declaration with a default integer type.

#line

Line number control.

long

Modificator for a long integer or float type.

#pragma

Change compiler settings.

register

Storage class to prefer a processor register.

restrict

Qualifier for non-overlapping memory areas.

return

Statement for returning from a function.

#sccs

Preprocessor directive for sccs.

short

Modificator for a short integer type.

signed

Modificator for a signed integer.

sizeof

Determines the type or object size.

static

Storage class for static variables.

struct

Declaration with a composite type.

switch

Initiates a switch structure.

typedef

Naming a custom type.

#unassert

Preprocessor directive for undefining predicates.

#undef

Preprocessor directive for undefining macros.

union

Declaration with a union type.

unsigned

Modificator for an unsigned integer.

void

Declaration with a type to ignore.

volatile

Qualifier for constant reevaluation.

#warning

Print a warning message.

wchar_t

Declaration with a wide character type.

while

Initiates a while loop or ends a do-while loop.