View Compilation Error

0_0_33158195_11805.cpp: In function 'int main()':
0_0_33158195_11805.cpp:9:34: error: 'memset' was not declared in this scope
         memset(a, '\0', sizeof(a));
                                  ^
0_0_33158195_11805.cpp:27:37: error: 'strcmp' was not declared in this scope
                 if(strcmp(a[i], a[k]) == 0)
                                     ^