View Compilation Error

0_0_7120188_27159.c:5: error: syntax error before '&' token
0_0_7120188_27159.c: In function `seqsum':
0_0_7120188_27159.c:8: error: `start' undeclared (first use in this function)
0_0_7120188_27159.c:8: error: (Each undeclared identifier is reported only once
0_0_7120188_27159.c:8: error: for each function it appears in.)
0_0_7120188_27159.c:9: error: `end' undeclared (first use in this function)
0_0_7120188_27159.c:10: error: `n' undeclared (first use in this function)
0_0_7120188_27159.c:12: error: `a' undeclared (first use in this function)