System.Copy - 从字符串或数组中复制

function Copy(
S: String;      {字符串或动态数组}
Index: Integer; {起始位置}
Count: Integer  {Copy 个数}
): String;        {如果参数 S 是动态数组, 这里也应该返回动态数组}



//从字符串中提取
var
ss,s: string;
begin
ss := 'CodeGear Delphi 2007';
s := Copy(ss,5,4);
ShowMessage(s);   {Gear}
end;

//从静态字符数组中截取字符串
var
arr: array[0..25] of Char;
s: string;
i: Integer;
begin
{给 arr 装入 26 个大写字母}
for i := Low(arr) to High(arr) do
arr[i] := Chr(i+65);

{提取}
s := Copy(arr, 1, 3);
ShowMessage(s);       {ABC}
end;

//从动态数组到动态数组
var
arr1,arr2 : array of Integer;
i: Integer;
begin
{设定数组大小}
SetLength(arr1, 10);

{给数组赋值}
for i := Low(arr1) to High(arr1) do
arr1[i] := i;

{执行 Copy; 注意: 之前没有给 arr2 设置大小, 就是设置了, 在这里也会被重置!}
arr2 := Copy(arr1, 0, 3);

for i in arr2 do
ShowMessage(IntToStr(i)); {会分别显示: 0、1、2}
end;

//关于起始位置(仅对字符串, 动态数组另当别论)
const
ss = 'ABCDEFG';
var
s: string;
begin
s := Copy(ss, 1, 3);
ShowMessage(s);        {ABC}
s := Copy(ss, 0, 3);
ShowMessage(s);        {ABC}
s := Copy(ss, -1, 3);
ShowMessage(s);        {ABC}
s := Copy(ss, -100, 3);
ShowMessage(s);        {ABC}
end;

//关于 Copy 个数
const
ss = 'ABCDEFG';
var
s: string;
begin
s := Copy(ss, 2, 6);
ShowMessage(s);               {BCDEFG}
s := Copy(ss, 2, Length(ss));
ShowMessage(s);               {BCDEFG}
s := Copy(ss, 2, MaxInt);
ShowMessage(s);               {BCDEFG}
end;


System 单元下的公用函数目录

posted on 2008-03-25 14:03  万一  阅读(...)  评论(...编辑  收藏