`static_assert` is a *keyword* defined in the `<assert.h>` header. It is available in the **C11** version of **C**.

`static_assert` is used to ensure that a condition is *true* when the code is compiled. 

> The condition must be a **constant expression**. In case of failure, an *error* message is displayed to alert the user. 

Here's the syntax:

```C
static_assert(expression, message);
```

#include <assert.h>
#include <stdio.h>
int main() {
  
  enum week_end { Sat, Sun, len = 2 };

  static_assert(len == 2, "The weekend is exactly 2 days.");

  printf("Success!");

}

Here, we've created an enumeration that represents the weekend. The `len` has been specifically assigned the integer constant `2`. Our static assertion verifies the condition `len == 2` and prints *Success !* on a successful compilation. Let's try changing the value for `len` as follows:

 

#include <assert.h>
#include<stdio.h>

int main() {
  
  enum week_end { Sat, Sun, len = 3 };

  static_assert(len == 2, "The weekend is exactly 2 days.");

  printf("Success!");

}

>In this case, we are dealt with a *compiler error*. The *error* message is displayed as expected.

What is static_assert in C?

Code