View Compilation Error

0_0_14723009_10885.cpp: In function 'int main()':
0_0_14723009_10885.cpp:19:20: error: 'strlen' was not declared in this scope
         if(strlen(x)==2)
                    ^
0_0_14723009_10885.cpp:37:30: error: 'strcmp' was not declared in this scope
                 if(strcmp(x,y)==0)
                              ^
0_0_14723009_10885.cpp:44:26: error: 'strcmp' was not declared in this scope
             if(strcmp(x,y)!=0)
                          ^