---
tags:
  - C
---

Booleans are a bit weird in C. _Oficially_ they don't exist as a core primitive
data type. Instead you use integers on the basis that:

> `0` is false and any non-zero value is true (but typically indicated with `1`)

Hence why the `int main()` [entrypoint](./Entry_point_to_C_programs.md) returns
`int`, because "success" is `1` and "error" is `0`.

A common example of this approach:

```c

int is_running = 1; // true
int has_error = 0; // false

if (is_running) {
    // Do stuff
}

```

Since the **C99** standard, a dedicated Boolean type has been available.

```c
#include <stdbool.h>

bool is_running = true;
bool has_error = false;

if (is_running) {
     // Do stuff
}
```

Note, you must include the bool header file which is part of the core in order
to have access to the `bool`, `true`, and `false` keywords.

This is just syntactic sugar though, and underneath it is just `int` values for
`0` and `1`.