View Compilation Error

0_0_36508220_7487.cpp: In function 'int main()':
0_0_36508220_7487.cpp:7:23: error: 'gets_s' was not declared in this scope
  while (gets_s(str, 80))
                       ^
0_0_36508220_7487.cpp:16:26: error: 'printf' was not declared in this scope
    case ' ':printf("%%20"); break;
                          ^
0_0_36508220_7487.cpp:26:14: error: 'printf' was not declared in this scope
   printf("\n");
              ^