Learn Best Keywords and Identifiers in C-Learncoding

Define Keywords and Identifiers in C Language

Keywords: Keyword is a reserved keyword in c language. It is used to create data types or identifiers. C language keyword are used to every c program used.

Keyword can not be used variable name.

Learn Best Keywords and Identifiers in C

auto	break	case
char	const	continue
default	do	double
else	enum	extern

float	for	goto
if	int	long
signed	sizeof	static
struct	switch	typedef

union	unsigned	void
volatile	while	malloc
calloc	realloc	free

Special Characters in C

     Special Characters in C Programming

,	.	_
-	:	;
{	}	(
#	$	!

^	&	*
?	/	|
\	"	%
%c	%d	%f

[	]	)
<	>	~
!	@	&*
%u	&a	%

C Keywords List or Description

Auto Keyword in C

Auto Keywords: The auto keyword defines automatic variables.

auto int variable_name;

This statement define that variable_name is storage class auto and data type int. automatic variables are local to a function, they are also called local variables. 

#include<stdio.h> #include<conio.h> void main() {  auto int a=100; printf("Value of a:%d", a); getch(); } **********OUTPUT********** Value of a:100

What is the use of break keyword in C

Break Keyword: A break keyword is used to terminates the loop immediately when it is encountered. break keyword is used to terminate the switch statement in c language.

#include<stdio.h> #include<conio.h> void main() {  int n; printf("Enter a number:"); scanf("%d", &n); switch(n) {   case 1:               printf("Case one executed");               break;  case 2:               printf("Case two executed");               break;  case 3:                printf("Case three executed");                break;  case 4:                printf("Case four executed");                break;  case 5:                printf("Case five executed");                break; default:               printf("invalid input"); } getch(); } **********OUTPUT********** Enter a number: 4 Case four executed

Continue Keyword in C

Continue Keyword: Continue keyword used to statement skips the statements after it inside the loop for iteration.

#include<stdio.h> #include<conio.h> void main() {    for(int i=1;i<=10;i++) {       if(i==3)        continue;        printf("%d\n",i); } getch(); } **********OUTPUT********** 1 2 4 5 6 7 8 9 10

Case Keyword in C

Case keyword: Case keyword used in switch statement. The switch statement is used if a block of statement can be executed among many blocks. 

#include<stdio.h> #include<conio.h> void main() {  int n; printf("Enter a number:"); scanf("%d", &n); switch(n) {   case 1:               printf("Case one executed");               break;  case 2:               printf("Case two executed");               break;  case 3:                printf("Case three executed");                break; default:               printf("invalid input"); } getch(); } **********OUTPUT********** Enter a number: 2 Case two executed

Char keyword in C

Char Keyword: Char keyword declared a character variable. char keyword use in character value define in c language.

#include<stdio.h> #include<conio.h> void main() {  char a='A'; printf("Character Value of a:%c", a); getch(); } **********OUTPUT********** Character Value of a:A

Const Keyword in C

Const keyword: Const keyword is used to constantly value. constant value never changes dynamically.

#include<stdio.h> #include<conio.h> void main() {  int x=500; printf("Value of x:%d", x); getch(); } **********OUTPUT********** Value of x:500

Do Keyword in C

do Keyword:Do keyword used to do-while loop in c language. It is very important in c language.

#include<stdio.h> #include<conio.h> void main() {  int i=1; do { printf("Value of i:%d ", i); while(i<=10); i=i+1; } getch(); } **********OUTPUT********** Value of i:1 2 3 4 5 6 7 8 9 10

Example of Double Data Type in C

#include<stdio.h> #include<conio.h> void main() {  double x=76800; printf("Value of x:%d", x); getch(); } **********OUTPUT********** Value of x:76800

Why is if-else used in C

if-else keyword: if-else keyword is used to decisions making in c language.

#include<stdio.h> #include<conio.h> void main() {  int age=18; if(age>=18); { printf("Your age is greater than18"); } else { printf("Your age is less than 18"); } getch(); } **********OUTPUT********** Your age is greater than18

Enum Keyword in C

Enum Keyword: Enumeration Keyword is used to collection of name integer constant. Enum is a user defined data type.

#include<stdio.h> #include<conio.h> enum week{Sunday=5,Monday=6,Thursday =7,Wednesday=9,Thursday=8, Friday=11,Saturday}; void main() {  enum week data; data=Wednesday; printf("Value data:%d", data); getch(); } **********OUTPUT********** Value of data:9

Extern Keyword in C

Extern keyword: Extern keyword used that a variable or function has external linking outside the file of declared.

File A.c #include<stdio.h> #include<conio.h> void main() {  int x=100; printf("Value of x:%d", x); getch(); } File B.c #include<stdio.h> #include<conio.h> #include extern A.c void main() {  extern int x; printf("Value of x:%d", x); getch(); } **********OUTPUT********** Value of x:100

Float Keyword in C

Float Keyword: Float keyword is used to floating point number stored in c language. float data types defferent size or range in c language.

#include<stdio.h> #include<conio.h> void main() {  float x=76.80; printf("Value of x:%f", x); getch(); } **********OUTPUT********** Value of x:76.80

Goto Keyword in C

Goto Keyword: Goto keyword is used to transfer the control of the program to the specified label in c program.

#include<stdio.h> #include<conio.h> void main() {  for(i=1; i<5; ++i) {     if (i==10)     goto level; } printf("i is not 10"); level:     printf("level, count cannot be 10"); getch(); } **********OUTPUT********** level, count cannot be 10

int Keyword in C

int keyword: A int keyword is used to declare integer type variables. integer data types can be holds only integer value.

#include<stdio.h> #include<conio.h> void main() {  int x=768; printf("Value of x:%d", x); getch(); } **********OUTPUT********** Value of x:768

Short, Long, Signed and Unsigned Data Types

Keyword: The short data type, long data type, signed and unsigned keywords are type modifiers that alter the meaning of a base data types in c language.

#include<stdio.h> #include<conio.h> void main() {  short int a=768;  long int b=65564; printf("Value of a:%d", a); printf("Value of b:%d", b); getch(); } **********OUTPUT********** Value of a:768 Value of b:65564

Return Keyword in C

return keyword: A return keyword can be used to terminates the function and returns the value of c language.

#include<stdio.h> #include<conio.h> int add() {     int a=10;     int b=20;     int c=a+b;     return c; } int main() {  printf("Value of c:%d",c); getch(); } **********OUTPUT********** Value of c:30

Sizeof keyword in C

sizeof keyword: A sizeof keyword is used to evaluates the size of data  value in c language.

#include<stdio.h> #include<conio.h> void main() {  int x=76; printf("size of x:%d", sizeof(x)); getch(); } **********OUTPUT********** Size of x:4

Register Keyword in C

Register Keyword: A register keyword is used to create register variables which are much faster than normal variables. because register variable nearby CPU.

#include<stdio.h> #include<conio.h> void main() {  register int x=76; printf("Value of x:%d", x); getch(); } **********OUTPUT********** Value of x:76

Static Keyword in C

Static Keyword: Static keyword use to create a static variable. Static variable are using static value.

#include<stdio.h> #include<conio.h> int add() { { static int i=0; printf("%d\n",i); i++; } } int main() {   add(); add();         add(); } **********OUTPUT********** 0 1 2

Struct Keyword in C

Struct Keyword: Struct keyword is used to collection of data or different data types. It is a user data types. 

#include<stdio.h> #include<string.h> struct Employee { int id; char name[50]; int salary; }; int main() {        struct Employee e[10];     int n; printf("Enter Employee Number:"); scanf("%d",&n); for(int i=0;i<n;i++) { printf("Enter Employee Id:"); scanf("%d",&e[i].id); printf("Enter Employee Name:");     scanf("%s",e[i].name); printf("Enter Employee Salary:"); scanf("%d",&e[i].salary); } printf("--------------------------------\n"); for(int i=0;i<n;i++) { printf("Employee Id:%d\n",e[i].id); printf("Employee Name:%s\n",e[i].name); printf("Employee Salary:%d\n",e[i].salary);     printf("--------------------------------\n"); } } **********OUTPUT********** Enter Employee Number:1 Enter Employee Id:6463 Enter Employee Name:Nivi Enter Employee Salary:67577 -------------------------------- Employee Id:6463 Employee Name: Nivi Employee Salary:67577

Union Keyword in C

Union Keyword: Union is a collection of data or different data types.union data types is a user defind data types. Union does not support multiple value. Union  can be store only one value at a time.

#include<stdio.h> #include<string.h> union Employee { int id; char name[50]; int salary; }; int main() {        union Employee e[10];     int n; printf("Enter Employee Number:"); scanf("%d",&n); for(int i=0;i<n;i++) { printf("Enter Employee Id:"); scanf("%d",&e[i].id); printf("Enter Employee Name:");     scanf("%s",e[i].name); printf("Enter Employee Salary:"); scanf("%d",&e[i].salary); } printf("--------------------------------\n"); for(int i=0;i<n;i++) { printf("Employee Id:%d\n",e[i].id); printf("Employee Name:%s\n",e[i].name); printf("Employee Salary:%d\n",e[i].salary);     printf("--------------------------------\n"); } } **********OUTPUT********** Enter Employee Number:1 Enter Employee Id:6463 Enter Employee Name:Nivi Enter Employee Salary:67577 -------------------------------- Employee Id:67577 Employee Name:∙☺ Employee Salary:67577

Typedef Keyword in C

Typedef Keyword: Typedef keyword is used to short name of long variale. it is most useful data types in c language.

#include<stdio.h> #include<conio.h> typedef struct learncoding {   int id; }learcoding; int main() {     learncoding lc; lc.id=457; printf("Id is:%d",lc.id); getch(); } **********OUTPUT********** Id is: 457

Void Keyword in C

Void Keyword: Void keyword is used to no return type void keyword no value

#include<stdio.h> #include<conio.h> void main()  // void keyword use in c program {  int x=400; printf("Value of x:%d", x); getch(); } **********OUTPUT********** Value of x:400