View Compilation Error

0_0_1103242_20695.c:3: error: syntax error before '&' token
0_0_1103242_20695.c: In function `ex_gcd':
0_0_1103242_20695.c:4: error: `b' undeclared (first use in this function)
0_0_1103242_20695.c:4: error: (Each undeclared identifier is reported only once
0_0_1103242_20695.c:4: error: for each function it appears in.)
0_0_1103242_20695.c:5: error: `x' undeclared (first use in this function)
0_0_1103242_20695.c:5: error: `y' undeclared (first use in this function)
0_0_1103242_20695.c:6: error: `a' undeclared (first use in this function)