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==Boolean Operator in C==

Character Set
Boolean Operator
&&
and
||
or
&& Operator
<OL><LI>&& operator: evaluate a Boolean expression from left to right.</LI><LI>Both sides of the operator must evaluate to true before the entire expression becomes true.</LI></OL>
|| Operator
<OL><LI>|| operator: evaluate from left to right.</LI><LI>If either side of the condition is true, the whole expression results in true.</LI></OL>

==Logical AND (&&) returns a true value if both relational expressions are true.==

Logical OR (||) returns true if any of the expressions are true.
Negations(!) return complements of values of relational expressions.
R1
R2
R1 && R2
R1 || R2
! R1
T
T
T
T
F
T
F
F
T
F
F
T
F
T
T
F
F
F
F
T
<OL><LI>Logical operators AND, and OR have higher priority than assignment operators.</LI><LI>Logical operators AND, and OR have lower priority than relational operators.</LI><LI>Negation operators have the same priority as unary operators.</LI></OL>

==Logical operator==

You can combine multiple relations or logical operations by logical operation.
The logical operators are negation (!), logical AND (&&), and logical OR (||),

<source lang="cpp">#include<stdio.h>
main(){
int c1 = 1,c2 = 2,c3 = 3;
if((c1 < c2) && (c1<c3)){
printf("\n c1 is less than c2 and c3");
}
if (!(c1< c2)){
printf("\n c1 is greater than c2");
}
if ((c1 < c2)||(c1 < c3)){
printf("\n c1 is less than c2 or c3 or both");
}
}</source>
<pre class=codeResult>c1 is less than c2 and c3
c1 is less than c2 or c3 or both</pre>

==Short circuiting==

When evaluating logical expressions, C uses the technique of short circuiting.

<source lang="cpp">C1 && C2 && C3 && C4</source>

==Ternary operator==

Ternary operators return values based on the outcomes of relational expressions.
The general form of the ternary operator is:

<source lang="cpp">(expr 1) ? expr2 : expr3</source>

==Testing letters with logic operator and (&&)==

<source lang="cpp">#include <stdio.h>
int main(void)
{
char letter =0;
printf("Enter an upper case letter:");
scanf(" %c", &letter);
if ((letter >= "A") && (letter <= "Z"))
{
letter += "a"-"A";
printf("You entered an uppercase %c.\n", letter);
}
else
printf("You did not enter an uppercase letter.\n");
return 0;
}</source>
<pre class=codeResult>Enter an upper case letter:R
You entered an uppercase r.</pre>

==The || is the logical OR operator.==

<source lang="cpp">#include <stdio.h>

int main()
{
char c;

printf("Y/y?");
c=getchar();
if(c=="Y" || c=="y")
{
printf("Bye!\n");
}
else
{
printf("Okay!\n");
}
return(0);
}</source>
<pre class=codeResult>Y/y?1
Okay!</pre>

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