View Compilation Error

0_0_38012086_28926.cpp: In function 'int main(int, char**)':
0_0_38012086_28926.cpp:7:13: error: 'atr' was not declared in this scope
  while(gets(atr))
             ^
0_0_38012086_28926.cpp:9:30: error: 'strcmp' was not declared in this scope
   if(!strcmp(str,"ENDOFINPUT"))break;
                              ^
0_0_38012086_28926.cpp:13:21: error: 'salpha' was not declared in this scope
    if(!salpha(str[i]))str[i]=((str[i]-'A')+26-5)%26+'A';
                     ^