There is no boolean variable type in C. Most people declare it as char (or unsigned char) and use the value 0 for false and 1 (or any value != 0) for true.
Through the use of #defines and typedefs, you can emulate it, though.
Code:
typedef unsigned char bool
#define TRUE 1
#define FALSE 0
Then just use the variable type bool and the values TRUE and FALSE.