How many keywords are there in c language?

There are 32 keywords in C language. According to the function of keywords, they can be divided into four categories: data type keywords, control statement keywords, storage type keywords and other keywords. There are 12 data type keywords, including char, double, float, int, etc.; there are 12 control statement keywords, including for, break, if, else, do, etc.; there are 4 storage type keywords, including auto, static , extern, etc.; there are 4 other keywords, including const, sizeof, etc.

The operating environment of this tutorial: windows7 system, c99 version, Dell G3 computer.

C language is concise, compact, easy to use and flexible. C language has a total of 32 keywords and 9 control statements. The program can be written in a free form and is case-sensitive. Combine the basic structures and statements of high-level languages ​​with the practicality of low-level languages. C language can operate on bits, bytes and addresses just like assembly language, and these three are the most basic working units of computers.

C language has a total of 32 keywords, as shown in the following table:

Keyword	Description
auto	Declare automatic variables
short	Declare short integer variables or functions
int	Declare an integer variable or function
long	Declare a long integer variable or function
float	Declare a floating-point variable or function
double	Declare a double-precision variable or function
char	Declare character variables or functions
struct	Declare structure variables or functions
union	Declaration of shared data types
enum	Declaration of enumeration types
typedef	Used to alias the data type
const	Declare read-only variables
unsigned	Declare unsigned type variables or functions
signed	Declare signed type variables or functions
extern	Declared variables are declared in other files
register	Declared register variables
static	Declare static variables
volatile	Indicates that variables can be changed implicitly during program execution
void	Declare a function with no return value or parameters, declare an untyped pointer
if	Conditional statement
else	Conditional statement negation branch (used with if)
switch	Use On switch statement
case	Switch statement branch
for	A kind of loop statement
do	The loop body of the loop statement
while	The loop condition of the loop statement
goto	Unconditional jump statement
continue	End the current loop and start the next cycle
break	Jump out of the current loop
default	The "other" branch in the switch statement
sizeof	Calculate data type length
return	Subroutine return statement (can be with or without parameters Parameters) Loop condition

C language keyword types

According to the function of keywords, they can be divided into four categories: data type keywords, control statement keywords, storage type keywords and other keywords. .

1. Data type keywords (12):

(1) char: declare a character variable or function
(2) double: declare a double precision variable or function Function
(3) enum: declares an enumeration type
(4) float: declares a floating-point variable or function
(5) int: declares an integer variable or function
(6) long: Declare a long integer variable or function
(7) short: declare a short integer variable or function
(8) signed: declare a signed type variable or function
(9) struct: declare a structure variable or Function
(10) union: declare a union (union) data type
(11) unsigned: declare an unsigned type variable or function
(12) void: declare a function with no return value or parameters, declare Untyped pointer (basically these three functions)

2. Control statement keywords (12):

• A loop statement
  (1) for: a kind of loop statement (can be understood but not expressed in words)
  (2) do: the loop body of the loop statement
  (3) while: the loop condition of the loop statement
  (4) break: jump out of the current loop
  (5) continue: End the current loop and start the next cycle

• B conditional statement
  (1)if: conditional statement
  (2)else: Conditional statement negation branch (used with if)
  (3)goto: unconditional jump statement

• C switch statement
  (1)switch: used for switch statement
  (2)case: switch statement branch
  (3)default: "other" branch in the switch statement

• D return statement
  return: subroutine return statement ( Parameters can be taken or not)

3. Storage type keywords (4)

(1)auto: Generally not used to declare automatic variables
(2)extern: Declaring variables is declared in other files (can also be regarded as reference variables)
(3)register: Declaring register variables
(4)static: Declaring static variables

4. Other keywords (4):

(1)const: declare read-only variables
(2)sizeof: calculate the length of the data type
(3)typedef: used to give Aliasing data types (of course there are other functions
(4)volatile: Indicates that variables can be changed implicitly during program execution

Related recommendations: "C Video Tutorial"

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