# ! the logical operator not in C

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In this article we will learn about the NOT operator, written as !. This operator reverses the result of the expression it operates on.

For example, if the expression evaluates to a non-zero value, then applying ! operator to it results into a 0. Vice versa, if the expression evaluates to zero then on applying ! operator to it makes it 1, a non-zero value. The final result (after applying !) 0 or 1 is considered to be false or true respectively.

## Example:

! ( y < 10 )

This means “not y less than 10”. In other words, if y is less than 10, the expression will be false, since ( y < 10 ) is true. We can express the same condition as ( y >= 10 ).

The NOT operator is often used to reverse the logical value of a single variable, as in the expression.

if ( ! flag )

This is another way of saying the same this as below :

if ( flag == 0 )

Does the NOT operator sound confusing? Avoid it if you want, as the same thing can be achieved without using the NOT operator.

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#### Satya Prakash

VOIP Expert: More than 8 years of experience in Asterisk Development and Call Center operation Management. Unique Combination of Skill Set as IT, Analytics and operation management.