View Compilation Error

23720_0_30899.c: In function `main':
23720_0_30899.c:13: error: syntax error before '/' token
23720_0_30899.c:25: error: `op' undeclared (first use in this function)
23720_0_30899.c:25: error: (Each undeclared identifier is reported only once
23720_0_30899.c:25: error: for each function it appears in.)
23720_0_30899.c:43: error: syntax error at end of input
13: er