View Compilation Error

1023880_0_0_15639.c:17: error: syntax error before '&' token
1023880_0_0_15639.c: In function `exgcd':
1023880_0_0_15639.c:19: error: `b' undeclared (first use in this function)
1023880_0_0_15639.c:19: error: (Each undeclared identifier is reported only once
1023880_0_0_15639.c:19: error: for each function it appears in.)
1023880_0_0_15639.c:21: error: `x' undeclared (first use in this function)
1023880_0_0_15639.c:22: error: `y' undeclared (first use in this function)
1023880_0_0_15639.c:23: error: `a' undeclared (first use in this function)