View Compilation Error

0_0_33693485_6172.cpp:37:2: error: missing terminating ' character
  else if(opt == '\')
  ^
0_0_33693485_6172.cpp: In function 'bool calc(long long int, long long int, long long int, char)':
0_0_33693485_6172.cpp:38:2: error: expected primary-expression before '{' token
  {
  ^
0_0_33693485_6172.cpp:38:2: error: expected ')' before '{' token
0_0_33693485_6172.cpp:42:1: error: expected primary-expression before '}' token
 }
 ^