View Compilation Error

0_0_5054102_12151.c:6: error: syntax error before '&' token
0_0_5054102_12151.c: In function `ex_Gcd':
0_0_5054102_12151.c:10: error: `b' undeclared (first use in this function)
0_0_5054102_12151.c:10: error: (Each undeclared identifier is reported only once
0_0_5054102_12151.c:10: error: for each function it appears in.)
0_0_5054102_12151.c:12: error: `x' undeclared (first use in this function)
0_0_5054102_12151.c:14: error: `y' undeclared (first use in this function)
0_0_5054102_12151.c:16: error: `a' undeclared (first use in this function)