ciabatta/docs/assert.md

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# assert.h - debug assertions
Macro definitions:
- [`assert(expr)`](#assert)
- [`static_assert`](#static-assert)
## [assert](#assert)
Assert a given condition is true, otherwise abort execution of a program.
The macro checks whether `expr` is true, and if not, prints the
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diagnostic information and then aborts execution in a way equivalent to calling
abort() function (See SIGABRT).
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If `_DEBUG` macro is defined, assert does not print a diagnostic message, and
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instead simply causes a debug break.
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If NDEBUG macro is defined assert expands to an empty statement. If both NDEBUG
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and `_DEBUG` are defined, then `_DEBUG` macro is ignored.
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```c
#if defined(NDEBUG)
#define assert(expr) ((void)0)
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#elif defined(`_DEBUG`)
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#define assert(expr) /* debug break */
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#else
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#define assert(expr) /* print diagnostic, then abort */
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#endif
```
<details>
<summary>Example</summary>
```c
// Uncomment to disable assert
//#define NDEBUG
#include <assert.h>
int factorial(int n) {
assert(n >= 0);
if(n == 0) return 1;
return n*factorial(n-1);
}
int main() {
printf("Factorial of %d is %d\n", 10, factorial(10));
printf("Factorial of %d is %d\n", -1, factorial(-1));
return 0;
}
```
The first function would print 3628800, the second would trigger an assert.
Output:
```
Factorial of 10 is 3628800
Assertion failed: n >= 0
Function: factorial
File: test\test_assert.c
Line: 4
Trace:
4: factorial
3: main
2: mainCRTStartup
1: BaseThreadInitThunk
0: RtlUserThreadStart
```
</details>
## [static_assert](#static-assert)
Keyword macro that expands to C11 keyword `_Static_assert`.
```c
#define static_assert _Static_assert
```