Keywords in C

What are keywords?
Keywords are set of special identifiers that are reserved by programming language itself. And they are not available to users to use as identifiers.  Keywords are also called as reserved words.

Below are the various keywords available in c programming language.

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

Note: 
keywords are always written in lower case.

Let us see how to use keywords in C program using a sample code.

 
  #include <stdio.h>
  void main() {
        int i = 0;
        const char ch = 'a';
        // value of ch is a.  So, case 'a' will be executed
        switch (ch) {
                case 'a':
                        // prints hello world for 3 times
                        for (i = 0; i < 3; i++)
                                printf("Hello world!!\n");
                        break;
                case 'b':
                        // prints hello world for 4 times
                        do {
                                printf("Hello Friend!!\n");
                                i++;
                        } while (i < 3);
                        break;

                default:
                        // prints unknow character
                        printf("Unknown character\n");
                        break;
        }
        return;
  }

  Output:

  jp@jp-VirtualBox:~$ ./a.out
  Hello world!!
  Hello world!!
  Hello world!!

Note: 
void, const, char, int, switch, case, for, while, do, break, default and return are the  keywords used in the above program.

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