[英]Populate integers to dropdownlist using a loop
无法弄清楚为什么我的程序不会使用循环填充我的DropDownList 。
到目前为止,我已经尝试过这两种情况:
'Fill in the year box from current year to 100 years ago.
'(Safe to assume no one over 100 will be signing up for site)
Dim CurYear As Integer = Date.Now.Year
Dim CurYearMinus100 As Integer = CurYear - 100
Dim Index As Integer = 0
Do While CurYear >= CurYearMinus100
DropDownListYear.Items.Insert(Index, CurYear)
Index += 1
CurYear -= 1
Loop
我也尝试使用.Add()
功能而不是insert:
Dim CurYear As Integer = Date.Now.Year
Dim CurYearMinus100 As Integer = CurYear - 100
Do While CurYear >= CurYearMinus100
DropDownListYear.Items.Add(Index)
CurYear -= 1
Loop
不确定为什么需要Index
,但这段代码可以正常工作:
Dim CurYear As Integer = Date.Now.Year
Dim CurYearMinus100 As Integer = CurYear - 100
Do While CurYear >= CurYearMinus100
DropDownListYear.Items.Add(New ListItem(CurYear.ToString(), CurYear.ToString()))
CurYear -= 1
Loop
我个人是For ... Next语句的粉丝,带有递减的Step参数。
可选的。 数字表达式。 计数器每次循环递增的量。
你的例子是:
Dim currentYear = Date.Now.Year
For year = currentYear To currentYear - 100 Step -1
DropDownListYear.Items.Add(New ListItem(year.ToString(), year.ToString()))
Next
替换这个:
DropDownListYear.Items.Insert(Index, CurYear)
附:
DropDownListYear.Items.Insert(Index, new ListItem(CurYear.ToString(), CurYear.ToString()))
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