List of all Keywords in C Language

This tutorial provides brief information on all 32 keywords in C programming.
List of keywords in C programming

Keywords in C Programming
auto
break
case
char
const
continue
default
do
double
else
enum
extern
float
for
goto
if
int
long
register
return
short
signed
sizeof
static
struct
switch
typedef
union
unsigned
void
volatile
while

Description of all Keywords in C


auto

The auto keyword declares automatic variables. For example:

auto int var1;

This statement suggests that var1 is a variable of storage class auto and type int. Variables declared within function bodies are automatic by default. They are recreated each time a function is executed. Since, automatic variables are local to a function, automatic variables are also called local variables. To learn more visit C storage class.


break and continue

The break statement makes program jump out of the innermost enclosing loop (while, do, for or switch statements) explicitly.

The continue statement skips the certain statements inside the loop.

for (i=1;i<=10;++i)
{
   if (i==3)
   continue;
   if (i==7)
   break;
   printf("%d ",i);
} 

Output

1 2 4 5 6

When i is equal to 3, continue statement comes into effect and skips 3. When i is equal to 7, break statement comes into effect and terminates the for loop. To learn more, visit C break and continue statement


switch, case and default

The switch and case statement is used when a block of statement has to be executed among many blocks. For example:

switch(expression)
{
    case '1':
    //some statements to execute when 1
    break;
    case '5':
    //some statements to execute when 5
    break;
    default:
    //some statements to execute when default;
}

Visit C switch statement to learn more.


char

The char keyword declares a character variable. For example:

char alphabet;

Here, alphabet is a character type variable.

To learn more, visit C data types.


const

An identifier can be declared constant by using const keyword.

const int a = 5;

To learn more, visit C data types.


do...while

int i;
do 
{
   print("%d ",i);
   i++;
}
while (i<10)

To learn more, visit C do...while loop


double and float

Keywords double and float are used for declaring floating type variables. For example:

float number;
double longNumber;

Here, number is single precision floating type variable whereas, longNumber is a double precision floating type variable.

To learn more, visit C data types


if and else

In C programming, if and else are used to make decisions.

if (i == 1)
   printf("i is 1.")
else
   prinf("i is not 1.")

If value of i is other than 1, output will be :

i is not 1

To learn more, visit C if...else statement


enum

Enumeration types are declared in C programming using keyword enum. For example:

enum suit
{
    hearts;
    spades;
    clubs;
    diamonds;
};

Here, a enumerated variable suit is created having tags: hearts, spades, clubs and diamonds.

To learn more, visit C enum


extern

The extern keyword declares that a variable or a function has external linkage outside of the file it is declared. To learn more, visit C storage type


for

There are three types of loops in C programming. The for loop is written in C programming using keyword for. For example:

for (i=0; i< 9;++i)
{
  printf("%d ",i);
}

Output

0 1 2 3 4 5 6 7 8

To learn more, visit C for loop


goto

The goto keyword is used for unconditional jump to a labeled statement inside a function. For example:

for(i=1; i<5; ++i)
{
    if (i==10)
    goto error;
}
printf("i is not 10");
error:
    printf("Error, count cannot be 10.");

Output

Error, count cannot be 10.

To learn more, visit C goto


int

The int keyword declares integer type variable. For example:

int count;

Here, count is a integer variable.

To learn more, visit C data types


short, long, signed and unsigned

The short, long, signed and unsigned keywodrs are type modifiers that alters the meaning of a base data type to yield new type.

short int smallInteger;
long int bigInteger;
signed int normalInteger;
unsigned int positiveInteger;
Range of int type data types
Data types Range
short int -32768 to 32767
long int -2147483648 to 214743648
signed int -32768 to 32767
unsigned int 0 to 65535

return

The return keyword terminates the function and returns the value.

int func()
{
    int b = 5;
    return b;
}

This function func() returns 5 to the calling function. To learn more, visit C user-defined functions.


sizeof

The sizeof keyword evaluates the size of a data (a variable or a constant).

#include <stdio.h>
int main()
{
    printf("%u bytes.",sizeof(char));
}

To learn more, visit C operators

Output

1 bytes.

register

The register keyword creates register variables which are much faster than normal variables.

register int var1;

static

The static keyword creates static variable. The value of the static variables persists until the end of the program. For example:

static int var;

struct

The struct keyword is used for declaring a structure. A structure can hold variables of different types under a single name.

struct student{
    char name[80];
     float marks;
     int age;
}s1, s2;

To learn more, visit C structures


typedef

The typedef keyword is used to explicitly associate a type with an identifier.

typedef float kg;
kg bear, tiger;

union

A Union is used for grouping different types of variable under a single name for easier handling.

union student 
{
    char name[80];
    float marks;
    int age;
}

To learn more, visit C unions


void

The void keyword indicates that a function doesn't return value.

void testFunction(int a)
{
  .....
}

Here, function testFunction( ) cannot return a value because the return type is void.


volatile

The volatile keyword is used for creating volatile objects. A volatile object can be modified in unspecified way by the hardware.

const volatile number

Here, number is a volatile object. Since, number is a constant variable, program cannot change it. However, hardware can change it since it is a volatile object.