Constants & their rules | keywords | operators | #Tut-02

 Content to be covered..

1. Constants

2. Rules to declare the constants

3. Keywords

4. Types of instruction

4. Operators

Constants

Constant in the program  is something what 

that does not change throughout the program.

Sometimes we need such a values in our program that should be remain as it is, so in such situation we

simply define constants.

In the fig. there are different types of constants are given. Most of the time we use integer and real constants.

Rules to declare constants

As we seen rules to declare the variables, there are some rules to declare the constants also.

lets see what are they..?

Code Snippet :

#include<stdio.h>

int main(){

    // integer constant

    const int a = -133;

    printf("%d\n", a);

    // a = 4; --> cannot change as 'a' is a constant

    // floating point constant

    const float pi = 3.14;

    printf("pi = %f\n", pi);

    // pi = 23.234; cannot change as 'pi' is a constant

    // character constant

    const char ch = 'k';

    printf("character = %c", ch);

    // ch = 'o'; --> cannot change as 'ch' is a constant

    // const char ch = 'abc'; --> throws an error

    return 0;

}

                                 

Keywords                                           

                        

Keywords are predefined, reserved words used in programming that have special meanings to the compiler. Keywords are part of the syntax and they cannot be used as an identifier.  

C Keywords

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

Types of instruction              

There are several types of instruction in a C programming. 

- Type declaration instruction

- Input/Output instruction

- Arithmetic instruction

- Control instruction

Code snippet:
                     

#include<stdio.h>

int main(){

    // type declaration instruction

    float number;

    // char c;

    double d;

    // arithmetic instruction

    int a=10, b=20, c, sum;

    c = a + b;

    printf("c = %d\n", c);

    return 0;

}  

                       

 control instruction..

So here we are done with the types of instruction.

Operators

An operator is a symbol which operates on a variable or value.

Operators in C