The difference between !a and a! in c language

In C language, the difference between !a and a! is: !a is a logical NOT operation, converting true values ​​into false, and false values ​​into true; and a! is a factorial operation, calculating the number a factorial.

The difference between !a and a! in c language

Direct answer:
In C language, !a represents logical NOT operation, and a! represents factorial operation.

Detailed explanation:

• Logical NOT operation (!a):

  • Convert true values ​​to false and false values ​​to true.
  • !0 The result is 1 (true), !1 The result is 0 (false).

• Factorial operation (a!):

  • Calculate the factorial of the number a.
  • 5!The result is 120, which is 1 x 2 x 3 x 4 x 5.

Example:

<code class="c">int a = 5;

printf("!a = %d\n", !a); // 输出0，因为5是非0值，因此其非值为假（0）
printf("a! = %d\n", a!); // 输出120，因为5的阶乘是120</code>

Note:

• The factorial operation must Performed on non-negative integers.
• If you try to calculate the factorial of a negative number, the program will generate an error.

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