View Compilation Error

0_0_19561329_15774.cpp: In function 'void search(node*, std::string, int)':
0_0_19561329_15774.cpp:72:27: error: 'strcpy' was not declared in this scope
             strcpy(ans,sum);
                           ^
0_0_19561329_15774.cpp:78:33: error: 'strlen' was not declared in this scope
     int L=strlen(tel[str[v]-'2']);
                                 ^
0_0_19561329_15774.cpp: In function 'int main()':
0_0_19561329_15774.cpp:125:23: error: 'strlen' was not declared in this scope
             L=strlen(p);
                       ^
0_0_19561329_15774.cpp:130:27: error: 'strcpy' was not declared in this scope
                 strcpy(q,p);
                           ^