View Compilation Error

0_0_31860123_14769.cpp: In function 'int main()':
0_0_31860123_14769.cpp:18:29: error: 'strcmp' was not declared in this scope
          if(strcmp(a[i],a[1])<0)
                             ^
0_0_31860123_14769.cpp:20:21: error: 'strcpy' was not declared in this scope
     strcpy(a[1],a[i]);                    
                     ^
0_0_31860123_14769.cpp:26:29: error: 'strcmp' was not declared in this scope
          if(strcmp(a[i],a[2])>0)
                             ^
0_0_31860123_14769.cpp:28:29: error: 'strcpy' was not declared in this scope
             strcpy(a[2],a[i]);
                             ^