View Compilation Error

0_0_20371775_7150.cpp: In function 'int main()':
0_0_20371775_7150.cpp:18:36: error: 'strcmp' was not declared in this scope
                 if(strcmp(a[i],a[j])==0) k++;
                                    ^
0_0_20371775_7150.cpp:23:30: error: 'strcpy' was not declared in this scope
                 strcpy(b,a[i]);
                              ^