View Compilation Error

0_0_27499423_26081.cpp: In function 'void search(node*, std::string, int)':
0_0_27499423_26081.cpp:73:27: error: 'strcpy' was not declared in this scope
             strcpy(ans,sum);
                           ^
0_0_27499423_26081.cpp:79:33: error: 'strlen' was not declared in this scope
     int L=strlen(tel[str[v]-'2']);
                                 ^
0_0_27499423_26081.cpp: In function 'int main()':
0_0_27499423_26081.cpp:126:23: error: 'strlen' was not declared in this scope
             L=strlen(p);
                       ^
0_0_27499423_26081.cpp:131:27: error: 'strcpy' was not declared in this scope
                 strcpy(q,p);
                           ^