Repeats the statements between the For...Next block a specified number of times.
For counter=start To end [Step step] statement-block [Exit For] statement-block Next [counter]
For Each item In list statement-block [Exit For] statement-block Next [item]
counter: Loop counter initially assigned the value to the right of the equal sign (start). Only numeric variables are valid. The loop counter increases or decreases according to the variable step until end is passed.
start: Numeric variable that defines the initial value at the beginning of the loop.
end: Numeric variable that defines the final value at the end of the loop.
step: Sets the value by which to increase or decrease the loop counter. If step is not specified, the loop counter is incremented by 1. In this case, end must be greater than start. If you want to decrease counter, end must be less than start, and step must be assigned a negative value.
As the counter variable is decreased, LibreOffice Basic checks if the end value has been reached. As soon as the counter passes the end value, the loop automatically terminates.
增量指定为 0 时，会一直重复执行「For」和「Next」之间的语句。
When counting down the counter variable, LibreOffice Basic checks for overflow or underflow. The loop ends when counter exceeds end (positive Step value) or is less than end (negative Step value).
「Exit For」语句可用于无条件退出循环。此语句必须位于「For...Next 循环内。If...Then」语句用于测试退出条件，如下所示:
For... statement-block If condition = True Then Exit For statement-block Next
In nested For...Next loops, if you exit a loop unconditionally with Exit For, only one loop is exited.
The following example uses two nested loops to sort a string array with 10 elements ( sEntry() ), that is filled with various contents:
Sub ExampleSort Dim sEntry(9) As String Dim iCount As Integer, iCount2 As Integer Dim sTemp As String sEntry = Array("Jerry","Patty","Kurt","Thomas","Michael",_ "David","Cathy","Susie","Edward","Christine") For iCount = 0 To 9 For iCount2 = iCount + 1 To 9 If sEntry(iCount) > sEntry(iCount2) Then sTemp = sEntry(iCount) sEntry(iCount) = sEntry(iCount2) sEntry(iCount2) = sTemp End If Next iCount2 Next iCount For iCount = 0 To 9 Print sEntry(iCount) Next iCount End Sub
This explores the content of an array to display each item it contains.
Sub list_iteration cutlery = Array("fork", "knife", "spoon") For Each item in cutlery Print item Next ' item End Sub