delphi - delphi中如何将字符串剪切为所需的数字？

Question

我有一个数据库列，它只能包含 40 个字符的字符串。因此，当字符串的长度大于 40 个字符时，就会出现错误。如何在delphi中将字符串剪切/修剪为40个字符？

Answer 1

var
  s: string;
begin
  s := 'This is a string containing a lot of characters.'
  s := Copy(s, 1, 40);
  // Now s is 'This is a string containing a lot of cha'

更奇特的是，如果字符串被截断，则添加省略号，以更清楚地表明这一点:

function StrMaxLen(const S: string; MaxLen: integer): string;
var
  i: Integer;
begin
  result := S;
  if Length(result) <= MaxLen then Exit;
  SetLength(result, MaxLen);
  for i := MaxLen downto MaxLen - 2 do
    result[i] := '.';
end;

var
  s: string;
begin
  s := 'This is a string containing a lot of characters.'
  s := StrMaxLen(S, 40)
  // Now s is 'This is a string containing a lot of ...'

或者，对于所有 Unicode 爱好者，您可以使用单个省略号字符保留两个以上的原始字符......(U+2026:水平省略号):

function StrMaxLen(const S: string; MaxLen: integer): string;
var
  i: Integer;
begin
  result := S;
  if Length(result) <= MaxLen then Exit;
  SetLength(result, MaxLen);
  result[MaxLen] := '…';
end;

var
  s: string;
begin
  s := 'This is a string containing a lot of characters.'
  s := StrMaxLen(S, 40)
  // Now s is 'This is a string containing a lot of ch…'

但是你必须确信你的所有用户及其亲属都支持这个不寻常的角色。