View Compilation Error

0_0_35096083_9457.cpp: In function 'int main()':
0_0_35096083_9457.cpp:10:1: error: expected initializer before 'for'
 for (int i = 0; i != a; ++i){
 ^
0_0_35096083_9457.cpp:10:17: error: 'i' was not declared in this scope
 for (int i = 0; i != a; ++i){
                 ^
0_0_35096083_9457.cpp:14:6: error: 'arr' was not declared in this scope
 sort(arr,arr+a);
      ^
0_0_35096083_9457.cpp:16:14: error: unable to deduce 'auto&&' from 'arr'
 for(auto &x: arr) {
              ^