pb 怎么把带小数的字符串转化成数值

用DOUBLE、dec、real等函数。
string ls_num
double ld_num
...
ld_num = double(ls_num)
if ld_num = 0 and ls_num <> "0" then//如果需要加上其它0.0,0.00...
messagebox("Error","Not a number")
end if