View Compilation Error

0_0_13739177_1556.cpp: In function 'int com(const void*, const void*)':
0_0_13739177_1556.cpp:4:48: error: 'strcmp' was not declared in this scope
     return strcmp((const char*)a,(const char*)b);
                                                ^
0_0_13739177_1556.cpp: In function 'int main()':
0_0_13739177_1556.cpp:18:38: error: 'strcmp' was not declared in this scope
             if(strcmp(arr[i],arr[i+1])==0){
                                      ^