difference( ) 函数示例

store 'smith' to gcname1
store 'smythe'  to gcname2
store 'smittie' to gcname3
store '' to gcname4
clear
? difference(gcname1, gcname2)  && 显示 4
? difference(gcname1, gcname3)  && 显示 4
? difference(gcname1, gcname4)  && 显示 1