View Compilation Error

51635_0_31420.c: In function `main':
51635_0_31420.c:6: error: `bool' undeclared (first use in this function)
51635_0_31420.c:6: error: (Each undeclared identifier is reported only once
51635_0_31420.c:6: error: for each function it appears in.)
51635_0_31420.c:6: error: syntax error before "c"
51635_0_31420.c:21: error: `c' undeclared (first use in this function)