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Логически оператор НЕ (!) в C

Този раздел ще обсъди логическия оператор НЕ (!) в езика за програмиране C. Както вече знаем, логическият оператор се използва за извършване на логическа операция чрез комбиниране на две или повече условия върху дадените изрази. Ако логическите условия на операндите са верни, операторът връща истински булеви стойности или 1. В противен случай той връща невярна булева стойност или 0. Логическите оператори се класифицират в три части: Логически оператори И, логическо ИЛИ и логическо НЕ.

Логически оператор НЕ (!) в C

The логически оператор И се използва за проверка на условията на два или повече операнда, които остават, дали са верни в даден израз; операторът И връща истинска или ненулева (1) стойност. В противен случай връща невярна или 0 стойност. И така, можем да кажем, че логическият оператор И може да работи само в израз, когато условията на двата операнда са верни, и ако някое условие не е истина, той връща 0. Логическият оператор И е представен като двоен амперсанд символ „&&“.

Синтаксис:

mysql изброява всички потребители
 (A > b && b > c) 

The логически оператор ИЛИ се използва за проверка на условията на двата операнда (A и B) и ако един от операндите или изразите е верен, операторът връща истинска булева стойност. По същия начин, ако нито един от изразите не е верен, той връща невярна или нулева стойност. Логическият оператор ИЛИ се обозначава като двойна тръба '||' символ.

Синтаксис:

 (A &gt; B) || (A <c) < pre> <h3>Logical NOT operator</h3> <p>The logical NOT operator is represented as the &apos;!&apos; symbol, which is used to reverse the result of any given expression or condition. If the result of an expression is non-zero or true, the result will be reversed as zero or false value. Similarly, if the condition&apos;s result is false or 0, the NOT operator reverses the result and returns 1 or true.</p> <p>For example, suppose the user enters a non-zero value is 5, the logical NOT (!) operator returns the 0 or false Boolean value. And if the user enters a zero (0) value, the operator returns the true Boolean value or 1. </p> <p> <strong>Syntax of the logical NOT operator</strong> </p> <pre> ! (condition); // It &apos;!&apos; represents the NOT operator </pre> <p>Here, the &apos;!&apos; symbol represents the logical NOT operator, which inverses the result of the given condition.</p> <h3>The truth table of the logical NOT operator:</h3> <p>Following is the truth table of the logical not operator in C</p> <pre> condition !(condition) 1 0 0 1 </pre> <h3>Example 1: Program to use the logical NOT operator in C</h3> <p>Let&apos;s create a simple program to reverse the given condition of the operands in the C programming language.</p> <pre> /* demonstration the use of the logical not operator in C. */ #include #include int main () { // declare an initialize x variable int x = 5; // display the result generated using the NOT (!) operator printf (&apos; The return value = %d 
&apos;, ! (x == 5)); printf (&apos; The return value = %d 
&apos;, ! (x != 5)); printf (&apos; The return value = %d 
&apos;, ! (x &gt;= 3)); printf (&apos; The return value = %d 
&apos;, ! (x <3)); return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> The return value = 0 The return value = 1 The return value = 0 The return value = 1 </pre> <p>In the above program, we use the NOT (!) operator to reverse the result of the various expression, such as the condition of the variable x is equal to 5, which is true. Still, the NOT operator reverses the result and returns 0. Similarly, we defined the condition (x!=5), but the logical operator changed its result and returned 1 and so on.</p> <h3>Example 2: Program to input a number to perform the logical NOT operator</h3> <p>Let&apos;s create a simple program to get the reverse result of an integer number using the logical NOT (!) operator in the C programming language.</p> <pre> /* demonstration the use of the logical not operator in C. */ #include #include int main () { // declare an initialize x variable int x, n; printf (&apos; Enter the number: &apos;); scanf (&apos;%d&apos;, &amp;x); n = !x; // use logical not operator to reverse the condition printf (&apos; The result of x: %d&apos;, n); // display the result return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> Enter the number: 7 The result of x: 0 </pre> <p>In the above program, we input an integer number 7 from the user and store it into x variable. After that, the logical NOT (!) operator reverses the value of x (non-zero) and returns zero (0) to print the result of x.</p> <p> <strong>2<sup>nd</sup> execution:</strong> </p> <pre> Enter the number: 0 The result of x: 1 </pre> <p>Similarly, we input zero (0) from the user and use the logical NOT (!) operator to reverse the value of x to a non-zero value, which is 1.</p> <h3>Example 3: Program to find the leap year using the logical AND (&amp;&amp;), OR (||), and NOT (!) operator</h3> <p>Let&apos;s write a simple program to check whether the given year is a leap or not using the logical AND (&amp;&amp;), logical OR (||), and the logical NOT (!) operator in the C language.</p> <pre> #include #include int main () { int yr; // declare int type variable printf (&apos; Enter the year: &apos;); scanf (&apos;%d&apos;, &amp;yr); // use the if..else statement to check the condition /* &apos;&amp;&amp;&apos; (AND) operator to validate both operand, &apos;||&apos; (OR) operator check ny given expressions are true, &apos;!&apos; (NOT) check the result of (yr % 100 != 0). */ if ( (yr % 400 == 0) || (yr % 4 == 0 &amp;&amp; yr % 100 != 0)) { printf (&apos; %d is a leap year. 
&apos;, yr); } else { printf (&apos; %d is not a leap year. 
&apos;, yr); } return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> Enter the year: 2020 2020 is a leap year. </pre> <p>In the above program, we enter 2020 and then check the given year by defining the if...else statement. In this statement, we defined two conditions;</p> <ol class="points"> <li>The given year is divided by 400, which is equal to 0. And then, we use the logical OR operator to check whether the left or right operand condition is true.</li> <li>In the second condition, the given year is divided by 4 and 100. But when we divide 2020 with 4, which is equal to 0. Similarly, we divide the year 2020 by 100, which is also not equal to 0. So, both the conditions are true that display the &apos;2020 is a leap year&apos;.</li> <li>But when we enter the year 2021, it prints the given result &apos;2021 is not a leap year&apos;.</li> </ol> <p> <strong>2<sup>nd</sup> execution:</strong> </p> <pre> Enter the year: 2021 2021 is not a leap year. </pre> <p> <strong>Example 4: Program to check different conditions using the AND, OR, and the NOT logical operator</strong> </p> <p>Let&apos;s write a program to demonstrate the multiple conditions of the given operands using the AND, OR, and the NOT logical operator in C.</p> <pre> /* program to check the various condition using the logical NOT operator in c. */ #include #include int main () { // declare and initialize variables int a = 20, b = 15; int n1 = 15, n2 = 17; // use logical &apos;AND&apos; and logical &apos;NOT&apos; operator if (a &gt; b &amp;&amp; a != 0) { printf (&apos; The AND (&amp;&amp;) operator said: Both conditions are true. 
 &apos;); } // use logical &apos;OR&apos; and logical &apos;NOT&apos; operator if (n1 &gt; n2 || n2 != 15) if ( ! (a &gt; b &amp;&amp; a != 0 )) { printf (&apos; The NOT (!) operator: Here both conditions are true. 
 &apos;); } else { printf (&apos; The NOT (!) operator: Here, both conditions are true. &apos; &apos; But, the status of the condition is reversed as false. 
&apos;); } return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> The AND (&amp;&amp;) operator is said: Both conditions are true. The OR (||) operator is said: Only one condition is true. The NOT (!) operator: Here, both conditions are true. But, the status of the condition is reversed as false. </pre> <hr></3));></pre></c)>

Ето, '!' символът представлява логическия оператор НЕ, който обръща резултата от даденото условие.

Таблицата на истинността на логическия оператор НЕ:

Следва таблицата на истинността на логическия оператор not в C

 condition !(condition) 1 0 0 1 

Пример 1: Програма за използване на логическия оператор NOT в C

Нека създадем проста програма за обръщане на даденото условие на операндите в езика за програмиране C.

 /* demonstration the use of the logical not operator in C. */ #include #include int main () { // declare an initialize x variable int x = 5; // display the result generated using the NOT (!) operator printf (&apos; The return value = %d 
&apos;, ! (x == 5)); printf (&apos; The return value = %d 
&apos;, ! (x != 5)); printf (&apos; The return value = %d 
&apos;, ! (x &gt;= 3)); printf (&apos; The return value = %d 
&apos;, ! (x <3)); return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> The return value = 0 The return value = 1 The return value = 0 The return value = 1 </pre> <p>In the above program, we use the NOT (!) operator to reverse the result of the various expression, such as the condition of the variable x is equal to 5, which is true. Still, the NOT operator reverses the result and returns 0. Similarly, we defined the condition (x!=5), but the logical operator changed its result and returned 1 and so on.</p> <h3>Example 2: Program to input a number to perform the logical NOT operator</h3> <p>Let&apos;s create a simple program to get the reverse result of an integer number using the logical NOT (!) operator in the C programming language.</p> <pre> /* demonstration the use of the logical not operator in C. */ #include #include int main () { // declare an initialize x variable int x, n; printf (&apos; Enter the number: &apos;); scanf (&apos;%d&apos;, &amp;x); n = !x; // use logical not operator to reverse the condition printf (&apos; The result of x: %d&apos;, n); // display the result return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> Enter the number: 7 The result of x: 0 </pre> <p>In the above program, we input an integer number 7 from the user and store it into x variable. After that, the logical NOT (!) operator reverses the value of x (non-zero) and returns zero (0) to print the result of x.</p> <p> <strong>2<sup>nd</sup> execution:</strong> </p> <pre> Enter the number: 0 The result of x: 1 </pre> <p>Similarly, we input zero (0) from the user and use the logical NOT (!) operator to reverse the value of x to a non-zero value, which is 1.</p> <h3>Example 3: Program to find the leap year using the logical AND (&amp;&amp;), OR (||), and NOT (!) operator</h3> <p>Let&apos;s write a simple program to check whether the given year is a leap or not using the logical AND (&amp;&amp;), logical OR (||), and the logical NOT (!) operator in the C language.</p> <pre> #include #include int main () { int yr; // declare int type variable printf (&apos; Enter the year: &apos;); scanf (&apos;%d&apos;, &amp;yr); // use the if..else statement to check the condition /* &apos;&amp;&amp;&apos; (AND) operator to validate both operand, &apos;||&apos; (OR) operator check ny given expressions are true, &apos;!&apos; (NOT) check the result of (yr % 100 != 0). */ if ( (yr % 400 == 0) || (yr % 4 == 0 &amp;&amp; yr % 100 != 0)) { printf (&apos; %d is a leap year. 
&apos;, yr); } else { printf (&apos; %d is not a leap year. 
&apos;, yr); } return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> Enter the year: 2020 2020 is a leap year. </pre> <p>In the above program, we enter 2020 and then check the given year by defining the if...else statement. In this statement, we defined two conditions;</p> <ol class="points"> <li>The given year is divided by 400, which is equal to 0. And then, we use the logical OR operator to check whether the left or right operand condition is true.</li> <li>In the second condition, the given year is divided by 4 and 100. But when we divide 2020 with 4, which is equal to 0. Similarly, we divide the year 2020 by 100, which is also not equal to 0. So, both the conditions are true that display the &apos;2020 is a leap year&apos;.</li> <li>But when we enter the year 2021, it prints the given result &apos;2021 is not a leap year&apos;.</li> </ol> <p> <strong>2<sup>nd</sup> execution:</strong> </p> <pre> Enter the year: 2021 2021 is not a leap year. </pre> <p> <strong>Example 4: Program to check different conditions using the AND, OR, and the NOT logical operator</strong> </p> <p>Let&apos;s write a program to demonstrate the multiple conditions of the given operands using the AND, OR, and the NOT logical operator in C.</p> <pre> /* program to check the various condition using the logical NOT operator in c. */ #include #include int main () { // declare and initialize variables int a = 20, b = 15; int n1 = 15, n2 = 17; // use logical &apos;AND&apos; and logical &apos;NOT&apos; operator if (a &gt; b &amp;&amp; a != 0) { printf (&apos; The AND (&amp;&amp;) operator said: Both conditions are true. 
 &apos;); } // use logical &apos;OR&apos; and logical &apos;NOT&apos; operator if (n1 &gt; n2 || n2 != 15) if ( ! (a &gt; b &amp;&amp; a != 0 )) { printf (&apos; The NOT (!) operator: Here both conditions are true. 
 &apos;); } else { printf (&apos; The NOT (!) operator: Here, both conditions are true. &apos; &apos; But, the status of the condition is reversed as false. 
&apos;); } return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> The AND (&amp;&amp;) operator is said: Both conditions are true. The OR (||) operator is said: Only one condition is true. The NOT (!) operator: Here, both conditions are true. But, the status of the condition is reversed as false. </pre> <hr></3));>

В горната програма използваме оператора NOT (!), за да обърнем резултата от различните изрази, като например условието на променливата x да е равно на 5, което е вярно. Все пак операторът NOT обръща резултата и връща 0. По същия начин дефинирахме условието (x!=5), но логическият оператор промени резултата си и върна 1 и т.н.

Пример 2: Програма за въвеждане на число за изпълнение на логическия оператор НЕ

Нека създадем проста програма за получаване на обратния резултат на цяло число, използвайки логическия оператор НЕ (!) в езика за програмиране C.

 /* demonstration the use of the logical not operator in C. */ #include #include int main () { // declare an initialize x variable int x, n; printf (&apos; Enter the number: &apos;); scanf (&apos;%d&apos;, &amp;x); n = !x; // use logical not operator to reverse the condition printf (&apos; The result of x: %d&apos;, n); // display the result return 0; } 

Изход:

 Enter the number: 7 The result of x: 0 

В горната програма въвеждаме цяло число 7 от потребителя и го съхраняваме в променлива x. След това логическият оператор NOT (!) обръща стойността на x (различна от нула) и връща нула (0), за да отпечата резултата от x.

2ndекзекуция:

 Enter the number: 0 The result of x: 1 

По същия начин въвеждаме нула (0) от потребителя и използваме логическия оператор NOT (!), за да обърнем стойността на x към ненулева стойност, която е 1.

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Пример 3: Програма за намиране на високосната година с помощта на логическия оператор И (&&), ИЛИ (||) и НЕ (!)

Нека напишем проста програма, която да проверява дали дадената година е високосна или не, използвайки логическия оператор И (&&), логическия ИЛИ (||) и логическия оператор НЕ (!) на езика C.

 #include #include int main () { int yr; // declare int type variable printf (&apos; Enter the year: &apos;); scanf (&apos;%d&apos;, &amp;yr); // use the if..else statement to check the condition /* &apos;&amp;&amp;&apos; (AND) operator to validate both operand, &apos;||&apos; (OR) operator check ny given expressions are true, &apos;!&apos; (NOT) check the result of (yr % 100 != 0). */ if ( (yr % 400 == 0) || (yr % 4 == 0 &amp;&amp; yr % 100 != 0)) { printf (&apos; %d is a leap year. 
&apos;, yr); } else { printf (&apos; %d is not a leap year. 
&apos;, yr); } return 0; } 

Изход:

 Enter the year: 2020 2020 is a leap year. 

В горната програма въвеждаме 2020 г. и след това проверяваме дадената година, като дефинираме израза if...else. В това твърдение дефинирахме две условия;

  1. Дадената година е разделена на 400, което е равно на 0. След това използваме логическия оператор ИЛИ, за да проверим дали условието на левия или десния операнд е вярно.
  2. Във второто условие дадената година е разделена на 4 и 100. Но когато разделим 2020 на 4, което е равно на 0. По същия начин разделяме годината 2020 на 100, което също не е равно на 0. И така, и двете условията са верни, които показват „2020 е високосна година“.
  3. Но когато въведем годината 2021, той отпечатва дадения резултат „2021 не е високосна година“.

2ndекзекуция:

 Enter the year: 2021 2021 is not a leap year. 

Пример 4: Програма за проверка на различни условия с помощта на логическия оператор И, ИЛИ и НЕ

Нека напишем програма, която да демонстрира множеството условия на дадените операнди, използвайки логическия оператор AND, OR и NOT в C.

 /* program to check the various condition using the logical NOT operator in c. */ #include #include int main () { // declare and initialize variables int a = 20, b = 15; int n1 = 15, n2 = 17; // use logical &apos;AND&apos; and logical &apos;NOT&apos; operator if (a &gt; b &amp;&amp; a != 0) { printf (&apos; The AND (&amp;&amp;) operator said: Both conditions are true. 
 &apos;); } // use logical &apos;OR&apos; and logical &apos;NOT&apos; operator if (n1 &gt; n2 || n2 != 15) if ( ! (a &gt; b &amp;&amp; a != 0 )) { printf (&apos; The NOT (!) operator: Here both conditions are true. 
 &apos;); } else { printf (&apos; The NOT (!) operator: Here, both conditions are true. &apos; &apos; But, the status of the condition is reversed as false. 
&apos;); } return 0; } 

Изход:

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 The AND (&amp;&amp;) operator is said: Both conditions are true. The OR (||) operator is said: Only one condition is true. The NOT (!) operator: Here, both conditions are true. But, the status of the condition is reversed as false.