View Compilation Error

0_0_16265781_32356.cpp: In function 'int main()':
0_0_16265781_32356.cpp:9:21: error: 'strcpy' was not declared in this scope
         strcpy(a,"1");
                     ^
0_0_16265781_32356.cpp:22:34: error: 'strlen' was not declared in this scope
                 length_a=strlen(a);
                                  ^
0_0_16265781_32356.cpp:57:23: error: 'strlen' was not declared in this scope
             d=strlen(b);
                       ^