View Compilation Error

0_0_21451503_19742.cpp: In function 'void Inhash(char*, char*)':
0_0_21451503_19742.cpp:31:23: error: 'strcpy' was not declared in this scope
  strcpy(Hq[AA].que,que);
                       ^
0_0_21451503_19742.cpp: In function 'int gethasha(char*)':
0_0_21451503_19742.cpp:51:27: error: 'strcmp' was not declared in this scope
   if(strcmp(str,Hq[tt].que)==0)
                           ^
0_0_21451503_19742.cpp: In function 'int gethashb(char*)':
0_0_21451503_19742.cpp:64:27: error: 'strcmp' was not declared in this scope
   if(strcmp(str,Hp[tt].ans)==0)
                           ^
0_0_21451503_19742.cpp: In function 'int main()':
0_0_21451503_19742.cpp:72:29: error: 'memset' was not declared in this scope
  memset(Head,-1,sizeof(Head));
                             ^
0_0_21451503_19742.cpp:108:23: error: 'strlen' was not declared in this scope
    int len=strlen(str1);
                       ^
0_0_21451503_19742.cpp:124:23: error: 'strlen' was not declared in this scope
    int len=strlen(str1);
                       ^