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
autodoubleintstruct
breakelselongswitch
caseenumregistertypedef
charexternreturnunion
continueforsignedvoid
doifstaticwhile
defaultgotosizeofvolatile
constfloatshortunsigned


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



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