## 数组竟然可以这样定义 转

涂孟超

``````//这是常规思路:
const
arr: array[0..1] of Char = ('A','B');
begin
ShowMessage(arr);                   {AB}
ShowMessage(IntToStr(Length(arr))); {2}
end;

//没想到可以这样:
const
arr: array[Boolean] of Char = ('A','B');
begin
ShowMessage(arr);                   {AB}
ShowMessage(IntToStr(Length(arr))); {2}

{访问元素}
ShowMessage(arr[False]);            {A}
ShowMessage(arr[True]);             {B}

{也可以这样访问}
ShowMessage(arr[Low(arr)]);         {A}
ShowMessage(arr[High(arr)]);        {B}

{但不能这样访问}
//  ShowMessage(arr[0]);
//  ShowMessage(arr[1]);

{但可以变通一下}
ShowMessage(arr[Boolean(0)]);       {A}
ShowMessage(arr[Boolean(1)]);       {B}
end;

//同理, 这样也可以:
const
arr: array[Byte] of Integer = (
1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,
30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,
56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,
82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,
106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,
146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,
166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,
186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,
206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,
226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,
246,247,248,249,250,251,252,253,254,255,256);
begin
ShowMessage(IntToStr(arr[Low(arr)]));  {1}
ShowMessage(IntToStr(arr[High(arr)])); {256}
ShowMessage(IntToStr(Length(arr)));    {256}
end;

//给这种用法来一个必要性的实例:
const
BoolStr: array[Boolean] of string = ('False', 'True');
var
b: Boolean;
begin
b := True;
ShowMessage(BoolStr[b]); {True}
b := not b;
ShowMessage(BoolStr[b]); {False}
end;

``````

### 涂孟超

ziluopao
2016/10/31
105
0
Java 数组转型和范型

2013/01/06
184
0
【vue源码】深度理解v-for

Sarva
05/06
0
0
Perl 6 语言的糟粕

2016/10/10
21
0
YUV420P/I420 stride 计算方式

Gobert
2017/07/04
0
0

1. 网页加载速度更快 在网站中使用CDN技术最直接的一个好处就是它可以加快网页的加载速度。首先，CDN加速的内容分发是基于服务器缓存的，由于CDN中缓存了不少数据，它能够给用户提供更快的页...

21分钟前
2
0

symbiochina88
32分钟前
2
0

SOM-TL437xF是一款广州创龙基于TI AM437x ARM Cortex-A9 + Xilinx Spartan-6 FPGA芯片设计的核心板，采用沉金无铅工艺的10层板设计，适用于高速数据采集和处理系统、汽车导航、工业自动化等领...

Tronlong创龙
33分钟前
2
0

好程序员Java学习路线分享MyBatis之线程优化，我们的项目存在大量用户同时访问的情况，那么就会出现大量线程并发访问数据库，这样会带来线程同步问题，本章我们将讨论MyBatis的线程同步问...

39分钟前
6
0
IDEA 自定义方法注解模板

IDEA 自定义方法注解模板 1、使用效果 /*** 计算交易费用* @Author wangjiafang* @Date 2019/9/11* @param feeComputeVo* @return*/@PostMapping("/v1/fee_compute")public ApiResp......

39分钟前
6
0