Question

我在这里有一个非常简单的代码，在运行控制台时会显示'你的卡是（随机数）（作为选择输入的数字）。当我瞄准控制台显示卡的套装时而不是用户输入的数字，我认为赋值语句将允许。

type
    Suit = array[1..4] of string;

var
  SuitChoice : Suit;
  I : integer;
  SuitName : string;
  Value : Integer;
  Index : integer;
  Choice : string;
begin
  randomize;
  Writeln('What is your suit?');
  readln(SuitChoice[i]);
  SuitChoice[1]:= 'Clubs';
  SuitChoice[2]:= 'Diamonds';
  SuitChoice[3]:= 'Hearts';
  SuitChoice[4]:= 'Spades';

  For index:= 1 to 13
  do
    Value:=Random(index);

  writeln('Your card is the ', Value, ' of ', SuitChoice[i]);
  readln;  
end.

Answer 1

您发布的代码存在一些问题。让我们一次一个地看看它们：

type
    Suit = array[1..4] of string;

var
  SuitChoice : Suit;
  I : integer;
  SuitName : string;
  Value : Integer;
  Index : integer;
  Choice : string;   { You declare but never use this variable, but
                       use i instead. Remove one of them. }
begin
  randomize;
  Writeln('What is your suit?');

  { You use an uninitialized variable to access the SuitChoice[] array }
  readln(SuitChoice[i]);

  { 
    You immediately overwrite anything you might have written (if the
    uninitialized value of i happened to be 1-4) with new values 
  }
  SuitChoice[1]:= 'Clubs';
  SuitChoice[2]:= 'Diamonds';
  SuitChoice[3]:= 'Hearts';
  SuitChoice[4]:= 'Spades';

  { 
    The next lines produce no output except for the final 
    Value := Random(13). There should be a begin..end block
    here, so that both the assignment to Value and the
    WriteLn execute each pass through the loop.
  }
  For index:= 1 to 13 do
    Value:=Random(index);

  writeln('Your card is the ', Value, ' of ', SuitChoice[i]);
  readln;  
end.

将所有这些放在一起应该会给你更多这样的东西：

program Cards;

type
    Suit = array[1..4] of string;
var
  SuitChoice : Suit;
  SuitName : string;
  Value : Integer;
  Index : integer;
  Choice : string;
begin
  randomize;

  SuitChoice[1]:= 'Clubs';
  SuitChoice[2]:= 'Diamonds';
  SuitChoice[3]:= 'Hearts';
  SuitChoice[4]:= 'Spades';


  { Write prompt, and read value into i.
  Writeln('What is your suit?');
  readln(Choice);

  { 
    Make sure we execute both the value assignment and the
    WriteLn on each pass through the loop 
  }
  for index:= 1 to 13 do
  begin
    Value := Random(index);
    WriteLn('Your card is the ', Value, ' of ', SuitChoice[Choice]);
  end;

  ReadLn;  
end.

由于您使用它的方式，您可以通过将SuitType更改为常量声明来稍微改善这一点。它可以在一行中完成，并保存初始化每个元素的代码，因为它是在编译时而不是运行时完成的。

const
  SuitChoice: array[1..4] of string = ('Clubs', 'Diamonds', 'Hearts', 'Spades');

然后，您可以完全删除SuitType类型，以及初始化它的4行，并将WriteLn语句更改为

WriteLn('Your card is the ', Value, ' of ', SuiteChoice[Choice]);

或者，IMO更简单地作为

WriteLn(Format('Your card is the %s of %s', [Value, SuitChoice[Choice]]));

Pascal写一个数组元素？

1 个答案: