Session 5 Relational Operator

RELATIONAL

9 is Big or Small
We need 2 numbers to compare

Maths  : > < >= <=   =  (Not)=
C lang : > < >= <=  ==  !=  Relational Operator
To Use Relational Operator we need 2 Number

5 > 3 YES  -> ENGLISH WORD
1 > 4 NO
Maths
5 > 3 TRUE  -> Boolean
1 > 4 FALSE
C- Lang
5 > 3 1
1 > 4 0
Result of Relational Operator in C/C++ is always Either 0 (False)or 1 (True)

a= 4>7; 0
a= 10>5; 1
a= 5>4; 1
a= 5<2; 0         = Assingment
a= 5<=3;0		 == Comparison
a= 9<=9; 1
a= 7!=2; 1
a= 9!=9; 0
a= 4=4; Error Lvalue Error
a= 5==4; 0
a= 5>5; 0
a= 5<5; 0
a= 5>=5; 1
a= 5!=5; 0
a= 5>; Expression Syntax Error
a = <= 8; Error ES
a= -10>=8; 0
a= 8 <= -25; 0
a= 6.5 <= 6.8; 1
a= 6.80 >= 6.8; 1
a= 6.0==6; 1
(==) Compares the value, not the data type
a= 0.75 <= 0.7; 0
a = 4>3>2; 0
a= 4 > 3 + 9 < 20; 1
a= 4 > 3 + 9 > 0; 0
Priority
1. * / %
2. + -
3. > < >= <=
4. == !=
5. =
=========================================
int  a = 5+6-2*5/3<=8+9>=7==1<=8+3*5>=6;
Step1    5+6-10/3<=8+9>=7==1<=8+3*5>=6;
Step2    5+6-3<=8+9>=7==1<=8+3*5>=6;
Step3    5+6-3<=8+9>=7==1<=8+15>=6;
Step4    11-3<=8+9>=7==1<=8+15>=6;
Step5    8<=8+9>=7==1<=8+15>=6;
Step6    8<=17>=7==1<=8+15>=6;
Step7    8<=17>=7==1<=23>=6;
Step8    1>=7==1<=23>=6;
Step9    0==1<=23>=6;
Step10   0==1>=6;
Step11   0==0;
Step12   1;
==========================================
a = 5*2-12>=90/12<=31-45*2>=56<1>12<=3*12-13!=5;
[5*2-12>=90/12<=31-45*2>=56<1>12<=3*12-13] !=5;
[Result is 0 or 1] != 5;  => 1

Since != has Least Priority, it will done atlast.
Relation operator in First Part [] will finally result either 0 or 1.
[0 or 1] != 5; So final result is 1 anyways
============================================
Ram is  4ft
Ragu is 3ft -->Ram is Taller than Ragu (4>2)
Ravi is 2ft -->Ragu is Taller than Ravi (3>2)--> Then Ram is also Taller than Ravi even without comparing (4>2)
Ram>Ragu>Ravi (4>3>2) which is true
But, a=4>3>2; Result in 0.
Because Result of 1st operation is Compared with next value.
We Must Compare Values with values not with result.
==============================================
Student 1 & 2 in Movie
Stu1 Says : I am Watching Movie
Stu2 Says : I am Eating popcorn  => This doesn't mean he is only eating popcorn
			It mean He is Watching Movie, Eating Popcorn.  here (,) is wrong so,
					He is Watching Movie and Eating Popcorn. And Conjuction is used, which gives logical.
SO, 10>4==4 wrong
	10>4 and 4==4 Correct
4>3>2 Logical error  a=4>3>2; => 0 Wrong
a= 4>3>2;
a= True>2; => Error False or True Cannot be compared with a value.
4>3 and 3>2 Logical Operator  a=4>3 && 3>2; => 1 Correct

Notes:
=> If we compile 2 or more relational operators directly then the result is unexpected. This is nothing but logical error.
=> To Overcome this, C people have introduced LOGICAL OPERATORS
=> The Purpose of Logical Operators is to combine two or more relation Statement and to get a compound Statement.

***************************************
Logical Operator  C,C++,Java     Python
1. Logical And       &&  		  and
2. Logical OR        ||  		  or
3. Logical NOT       !   		  not
-------------------------------------------------------------------------------
Logical Operator Table
=====================
  Arg1       *     Arg2    *  Arg1 && Arg2  *  Arg1 || Arg2  *  !Arg1  *  !Arg2
  Zero       *     Zero    *       0        *        0       *    1    *   1
  Zero       *   Non-Zero  *       0        *        1       *    1    *   0
Non-Zero     *	   Zero    *       0        *        1       *    0    *   1
Non-Zero     *   Non-Zero  *       1        *        1       *    0    *   0
------------------------------------------------------------------------------------
Username  AND   Password    Login
Correct			Correct       1
Correct  		Wrong		  0
Wrong			Correct		  0
Wrong		    Wrong 		  0

8 && 45 => 1
0 && 45 => 0
8 && 0  => 0
0.2 && -45 => 1
1 &&   => ES Error
200 && 0.0 => 0

Payment Portal => Debit Card OR  UPI txn
Completing any one payment method will be successfull.

10 || 0 => 1
0 || 0 => 0
0 || 8.32 => 1
0.0 || 0.6 => 1
0 ||  => ES Error

Logical NOT  (!)
!(Non zero  Except 0) => 0
!(Zero) => 1
Logical NOT Syntax >>>>>![Arg]<<<<<<
!200 =>  0
!90.4=> 0
!45 =>  0
!-98=> 0
!0 => 1
! .0 =>1
! 0.0 => 1
//////////////////////////////////////////////////////////
Binary => &&  ||   ==   !=  * % / + - = > < >= <=     Since It needs Both side for operation

Unary  =>  ! 	It needs only Ride side for operation
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Priority
1.  !            R to L
2.  * / %        L to R
3. + -  		 L to R
4. > < >= <=     L to R
5. == !=		 L to R
6. &&			 L to R
7. ||			 L to R
8. =			 R to L
----------------------------------------------------------------
a= 2+3+4+5;    14   L to R
a= !!!!!!!25;   0   R to L

void main ()
{
int a;
a=4;
!!!!a;   => Not Stored back in a
printf("%d",a); 0 1 1 1 4
}