View Compilation Error

0_0_32278189_7316.cpp: In function 'int main()':
0_0_32278189_7316.cpp:12:19: error: 'strlen' was not declared in this scope
   int m = strlen(s),a[5] = {0};
                   ^
0_0_32278189_7316.cpp:16:6: error: 'a' was not declared in this scope
      a[0]++;
      ^
0_0_32278189_7316.cpp:18:6: error: 'a' was not declared in this scope
      a[1]++;
      ^
0_0_32278189_7316.cpp:20:6: error: 'a' was not declared in this scope
      a[2]++;
      ^
0_0_32278189_7316.cpp:22:6: error: 'a' was not declared in this scope
      a[3]++;
      ^
0_0_32278189_7316.cpp:24:6: error: 'a' was not declared in this scope
      a[4]++;
      ^
0_0_32278189_7316.cpp:26:15: error: 'a' was not declared in this scope
   cout<<"a:"<<a[0]<<endl;
               ^