从TStringList删除空字符串 [英] Remove empty strings from TStringList

问题描述

Delphi中是否有任何内置函数可以删除 TStringList 中所有为空的字符串？

Is there any build-in function in Delphi to remove all strings from a TStringList which are empty?

如何在列表中循环删除这些项目？

How to loop through the list to remove these items?

推荐答案

要回答您的第一个问题，没有内置函数。手动循环很容易。这应该做到这一点：

To answer your first question, there is no built in function for that. Looping manually is easy. This should do it:

for I := mylist.count - 1 downto 0 do
begin
  if Trim(mylist[I]) = '' then
    mylist.Delete(I);
end;

请注意，为此，for循环必须从Count-1开始向下遍历该列表，直到0

Note that the for loop must traverse the list in reverse starting from Count-1 down to 0 for this to work.

使用 Trim（）是可选的，具体取决于您是否要删除包含以下内容的字符串还是空白。如果mylist [I] =''将 if 语句更改为，则将仅删除完全为空的字符串。

The use of Trim() is optional, depending on whether you want to remove strings that contain just whitespace or not. Changing the if statement to if mylist[I] = '' then will remove only completely empty strings.

以下是显示正在运行的代码的完整例程：

Here is a full routine showing the code in action:

procedure TMyForm.Button1Click(Sender: TObject);
var
  I: Integer;
  mylist: TStringList;
begin
  mylist := TStringList.Create;
  try
    // Add some random stuff to the string list
    for I := 0 to 100 do
      mylist.Add(StringOfChar('y', Random(10)));
    // Clear out the items that are empty
    for I := mylist.count - 1 downto 0 do
    begin
      if Trim(mylist[I]) = '' then
        mylist.Delete(I);
    end;
    // Show the remaining items with numbers in a list box
    for I := 0 to mylist.count - 1 do
      ListBox1.Items.Add(IntToStr(I)+' '+mylist[I]);
  finally
    mylist.Free;
  end;
end;

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