KEIL C中的警告语句什么意思？？？
*** WARNING L1: UNRESOLVED EXTERNAL SYMBOLSYMBOL: ?C?FCASTL
MODULE: GongPin.obj (GONGPIN)
*** WARNING L1: UNRESOLVED EXTERNAL SYMBOL
SYMBOL: ?C?CASTF
MODULE: GongPin.obj (GONGPIN)
*** WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL
SYMBOL: ?C?FCASTL
MODULE: GongPin.obj (GONGPIN)
ADDRESS: 0C45H
*** WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL
SYMBOL: ?C?CASTF
MODULE: GongPin.obj (GONGPIN)
ADDRESS: 0C50H
这4个warnings是说的什么问题？？？
