View Compilation Error

0_0_35089824_30502.cpp: In function 'int isprime(int)':
0_0_35089824_30502.cpp:27:2: error: expected primary-expression before '?' token
  ?
  ^
0_0_35089824_30502.cpp:30:2: error: expected primary-expression before '}' token
  }
  ^
0_0_35089824_30502.cpp:30:2: error: expected ':' before '}' token
0_0_35089824_30502.cpp:30:2: error: expected primary-expression before '}' token
0_0_35089824_30502.cpp: In function 'int main()':
0_0_35089824_30502.cpp:130:9: error: expected primary-expression before '=' token
    ans ?= 0;
         ^
0_0_35089824_30502.cpp:130:12: error: expected ':' before ';' token
    ans ?= 0;
            ^
0_0_35089824_30502.cpp:130:12: error: expected primary-expression before ';' token