View Compilation Error

0_0_18880556_11372.cpp: In function 'int main()':
0_0_18880556_11372.cpp:4:17: error: 'scanf' was not declared in this scope
   scanf("%d", &T);
                 ^
0_0_18880556_11372.cpp:7:17: error: 'str' was not declared in this scope
     scanf("%s", str);
                 ^
0_0_18880556_11372.cpp:8:23: error: 'strlen' was not declared in this scope
     int len=strlen(str);
                       ^
0_0_18880556_11372.cpp:23:23: error: 'printf' was not declared in this scope
     printf("%d\n", res);
                       ^