# Logical Operators

### 1. Logical AND(&&/and).

There are two Logical AND Operators, First * &&* and 2nd

**where First Operator has higher precedence(means higher priority) than 2nd. It Compares two expressions or operators and gives output in 4 cases.**

*and**See the Below image.*

**Case 1.** When Both the expressions are *true* then it returns ** True**.

**For Example :- ** * (5>2)&&(5<8) *

In the above Example, It returns ** True** because both the expressions are

*true*.

**Case 2.** When 1st expression is *true *and 2nd is *false *then it returns ** False**.

**For Example :-** *(3<5)&&(5<2)*

In the above Example, 1st expression is *true* but 2nd expression is *false* then it returns ** False**.

**Case 3.** When 1st expression is *false* and 2nd is *true *then it returns ** False**.

**For Example :-** *(5<2)&&(3<5)*

In the above Example, 1st expression is *false* but 2nd expression is *true* then it returns ** False**.

**Case 4.** When Both the Expression is *false* then it also returns * False*.

**For Example :-** *(6<2)&&(3>5)*

In the above Example, Both expressions are *false* then it returns ** False**.

### 2. Logical OR(**||**/or).

**||**

There are Two Logical OR, First **||** and 2nd ** or** where First Operator has higher precedence(means higher priority) than 2nd. It Compares two expressions or operators and gives output in 4 cases.

*See the Below image.*

**Case 1.** When Both the expressions are *true* then it returns ** True**.

**For Example :-** *(5>2) ||(5<8)*

In the above Example, It returns ** True** because both the expressions are

*true*.

**Case 2.** When 1st expression is *true *and 2nd is *false *then it returns ** True**.

**For Example :-** *(3<5) ||(5<2)*

In the above Example, 1st expression is *true* but 2nd expression is *false* then it returns ** True**.

**Case 3.** When 1st expression is *false* and 2nd is *true *then it returns ** True**.

**For Example :-** *(5<2)***||***(3<5)*

In the above Example, 1st expression is *false* but 2nd expression is *true* then it returns ** True**.

**Case 4.** When Both the Expression is *false* then it also returns * False*. For

**Example :-** *(6<2)***||***(3>5)*

In the above Example, Both expressions are *false* then it returns ** False**.

### 3. Logical NOT(!).

It returns the reverse value of expression means when the expression is *true* then it returns ** False**, and when the expression is

*false*then it returns

*True.***For Example :-** * !(3<2)*

In the above example, the expression is *false* but it returns ** True**.

### 4. Exclusive OR(xor).

When both the expression are Identical (means both are *true* or *false*) then it returns ** False** and when any one of them is

*true*then it returns

**.**

*True**See the below image.*

**Case 1.** When Both the expressions are *true* or *false* then it returns ** False**.

**For Example :-** *(5>2)xor(5<8)* or *(6<2)***||***(3>5)*

In the above example, both the expressions in the first example is *true* and both the expressions in the second example is *false* so both the examples return * False*.

**Case 2.** When 1st expression is *true *and 2nd is *false *then it returns ** True**.

**For Example :- ** *(3<5)xor(5<2)*

In the above Example, 1st expression is *true* but 2nd expression is *false* then it returns ** True**.

**Case 3.** When 1st expression is *false* and 2nd is *true *then it returns ** True**.

**For Example :-** *(5<2)xor(3<5)*

In the above Example, 1st expression is *false* but 2nd expression is *true* then it returns ** True**.

# Increment and Decrement Operators.

** Increment Operator:- ** It increases the value of the variable by 1. It is of two types:

** 1. Pre-increment:- ** It first increases the value of variable, then uses the new variable value.

**For Example:-** **++$a**

*<?php $a=40; echo ++$a; ?>*

**Output :-** 41

2. ** Post-increment:-** First uses the current value of the variable, then increases the value of variable by 1.

**For Example:-** **$a++**

*<?php $a=25; echo $a++.”<br>”; echo $a; ?>*

**Output:-** 25

26

** Decrement Operator:-** It decreases the value of the variable by 1. It is of two types:

** 1. Pre-decrement:- ** It first decreases the value of the variable, then uses the new variable value.

**For Example:-** ** – – $a**

*<?php $a=40; echo – – $a; ?>*

**Output :-** 39

2. ** Post-decrement:-** First uses the current value of the variable, then decreases the value of the variable by 1.

**For Example:-** **$a- –**

*<?php $a=25; echo $a – -.”<br>”; echo $a; ?>*

**Output:-** 25

24