assert.h documentation

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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.
<details><summary>Description</summary>
The macro checks whether `expr` is true, and if not, prints the
information about where the error occurs and then aborts execution in a way
equivalent to calling abort() function (See SIGABRT).
You can disable the assertion checks by defining NDEBUG macro.
</details>
<details><summary>Declaration</summary>
```c
#if defined(NDEBUG)
#define assert(expr) ((void)0)
#else
#define assert(expr) /* see description */
#endif
```
</details>
<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`.
<details>
<summary>Definition</summary>
```c
#define static_assert _Static_assert
```
</details>

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# Ciabatta
Ciabatta is a C standard library implementation. The goal is to provide a
cross-platform implementation that provides it's own documentation, clarifying
implementation-defined details, as well as provides additional functionality,
like sockets, or unicode processing, the kind of functionality that is used
in different kinds of programs.
## Headers
The implementation doesn't provide all headers. The headers that aren't
provided are supposed to be provided by compiler. The list of such headers:
- float.h
- iso646.h
- limits.h
- stdalign.h
- stdarg.h
- stdbool.h
- stddef.h
- stdint.h
- stdnoreturn.h
The headers that are provided have documentation included:
- [assert.h](assert.md)
- [complex.h](complex.md)
- [ctype.h](ctype.md)
- [errno.h](errno.md)
- [fenv.h](fenv.md)
- [inttypes.h](inttypes.md)
- [locale.h](locale.md)
- [math.h](math.md)
- [signal.h](signal.md)
- [stdio.h](stdio.md)
- [stdlib.h](stdlib.md)
- [string.h](string.md)
- [tgmath.h](tgmath.md)
- [threads.h](threads.md)
- [time.h](time.md)
- [uchar.h](uchar.md)
- [wchar.h](wchar.md)
- [wctype.h](wctype.md)

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#include <assert.h>
#include <stddef.h>
#include <errno.h>
void do_more_stuff(char *ptr) {
assert(ptr != NULL);
}
void do_stuff() {
do_more_stuff(NULL);
int factorial(int n) {
assert(n >= 0);
if(n == 0) return 1;
return n*factorial(n-1);
}
int main() {
errno = 0;
assert(2+2 == 4);
do_stuff();
}
printf("Factorial of %d is %d\n", 10, factorial(10));
printf("Factorial of %d is %d\n", -1, factorial(-1));
return 0;
}