View Compilation Error

0_0_33863828_14614.cpp: In function 'int main()':
0_0_33863828_14614.cpp:35:41: error: 'memset' was not declared in this scope
   memset(front_arr, 0, sizeof(front_arr));
                                         ^
0_0_33863828_14614.cpp:44:26: error: 'strlen' was not declared in this scope
    int lenth = strlen(str);
                          ^