How do I share variables between different .c files?

Question

How can I use a variable in one `.c` file when it has been previously defined in another `.c` file?

Accepted Answer

In fileA.c:

```
int myGlobal = 0;
```

In fileA.h

```
extern int myGlobal;
```

In fileB.c:

```
#include "fileA.h"
myGlobal = 1;
```

So this is how it works:

- the variable lives in fileA.c

- fileA.h tells the world that it exists, and what its type is (`int`)

- fileB.c includes fileA.h so that the compiler knows about myGlobal before fileB.c tries to use it.

Solution