View Compilation Error

111811_0_32662.c: In function `main':
111811_0_32662.c:5: error: `a' undeclared (first use in this function)
111811_0_32662.c:5: error: (Each undeclared identifier is reported only once
111811_0_32662.c:5: error: for each function it appears in.)
111811_0_32662.c:5: error: `b' undeclared (first use in this function)