View Compilation Error

0_0_15879047_16109.cpp: In function 'int sr(int, int, int)':
0_0_15879047_16109.cpp:17:12: error: return-statement with no value, in function returning 'int' [-fpermissive]
  if (!len) return;
            ^
0_0_15879047_16109.cpp:20:31: error: 'sio' was not declared in this scope
   sio(po[i], e + 1, e + len, i);
                               ^
0_0_15879047_16109.cpp: In function 'int sl(int, int, int)':
0_0_15879047_16109.cpp:26:12: error: return-statement with no value, in function returning 'int' [-fpermissive]
  if (!len) return;
            ^
0_0_15879047_16109.cpp:29:31: error: 'sio' was not declared in this scope
   sio(po[i], e - len, e - 1, i);
                               ^