Keywords in C
Keywords are reserved words in C, which a programmer must not use for other purposes. In C11 standard there are totally 44 keywords which are as follows:
| auto |
if |
unsigned
|
| break |
inline |
void
|
| case |
int |
volatile
|
| char |
long |
while
|
| const |
register |
_Alignas
|
| continue |
restrict |
_Alignof
|
| default |
return |
_Atomic
|
| do |
short |
_Bool
|
| double |
signed |
_Complex
|
| else |
sizeof |
_Generic
|
| enum |
static |
_Imaginary
|
| extern |
struct |
_Noreturn
|
| float |
switch |
_Static_assert
|
| for |
typedef |
_Thread_local
|
| goto |
union |
|
|
|
Language limits
Any C compiler (conforming to C11 standard) should be able to handle the following cases:
- 127 nesting levels of blocks
- 63 nesting levels of conditional inclusion
- 63 nesting levels of parenthesized declarators within a full declarator
- 63 nesting levels of parenthesized expressions within a full expression
- 63 significant initial characters in an internal identifier or a macro name
- 31 significant initial characters in an external identifier
- 4095 external identifiers in one translation unit
- 511 identifiers with block scope declared in one block
- 4095 macro identifiers simultaneously defined in one preprocessing translation unit
- 127 parameters in one function definition
- 127 arguments in one function call
- 127 parameters in one macro definition
- 127 arguments in one macro invocation
- 4095 characters in a logical source line
- 4095 characters in a string literal (after concatenation)
- 65535 bytes in an object (in a hosted environment only)
- 15 nesting levels for #included files
- 1023 case labels for a switch statement (excluding those for any nested switch
statements)
- 1023 members in a single structure or union
- 1023 enumeration constants in a single enumeration
- 63 levels of nested structure or union definitions in a single struct-declaration-list
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