How to fix C error ‘unknown type name bool’

Problem:

You have C code like

bool mybool;

but when you try to compile it you see an error message like

main.c: In function ‘main’:
main.c:3:5: error: unknown type name ‘bool’; did you mean ‘_Bool’?
     bool mybool;
     ^~~~
     _Bool

Solution:

Add

#include <stdbool.h>

at the top of the source file where the error occured.

The reason for this error is that bool is not a standard type in C (like int or char) but only in stdbool.h.