/in/foo.c: In function 'main':
/in/foo.c:10:10: warning: left-hand operand of comma expression has no effect [-Wunused-value]
  for(xmin,xmin<=xmax,xmin++)
          ^
/in/foo.c:10:21: warning: left-hand operand of comma expression has no effect [-Wunused-value]
  for(xmin,xmin<=xmax,xmin++)
                     ^
/in/foo.c:10:28: error: expected ';' before ')' token
  for(xmin,xmin<=xmax,xmin++)
                            ^
/in/foo.c:10:28: error: expected expression before ')' token