Question

我的手上有一个非常简单的Ada项目。任务是收集“选民”的投票并将其与每个“候选人”的得分进行比较，并确定哪个候选人最适合选民。

输入如下所示，然后输出应该输出：

Input:
0   0   0   1   1   1  -1  -1  -1   1
7
A   
1   1   1   1   1   1   1   1   1   1
B  
-1  -1  -1  -1  -1  -1  -1  -1  -1  -1
C   
1  -1   1  -1   1  -1   1  -1   1  -1
D   
1   0   1   0   1   0   1   0   1   0
E   
0  -1   0  -1   0  -1   0  -1   0  -1
F   
1   1   1   1   0   0   0   0   0   0
G   
0   0   0   1  -1   0   0  -1   1   1

Output:

A
F
G

到目前为止，我有一个程序会接受每位候选人的投票，并将其与选民的投票进行比较。我知道我需要做什么，因为我以前用Java做过，但我不知道如何在Ada中接受输入。这是我到目前为止所拥有的。

with Ada.Text_IO, Ada.Integer_Text_IO;
use Ada.Text_IO, Ada.Integer_Text_IO;

procedure Candidates is
-- take an array of candidates and determine which candidate best matches
-- the user's votes, then return those candidates
    Number_Of_Candidates: Integer;
subtype VoterArray_Index is Integer range 1..10;
subtype CandidatesArray_Index is Integer range 1..Number_Of_Candidates;
type VoterArray is array(VoterArray_Index) of Integer;
type CandidatesArray is array(Character range 'A' .. 'Z') of array;
type Best_CandidatesArray is array(CandidatesArray_Index) of array;

Voter: VoterArray;
Candidates: CandidatesArray;
Best_Candidates: Best_CandidatesArray;

function Get_Input() is
-- get the input and put it into the correct arrays
    Current_Line : string; 

    begin
        Get(Current_Line);

function Get_Best_Score(CandidatesArray: in out CandidatesArray) is
-- go through the arrays and find the best score
    SameAnswers: Integer;
    DifferentAnswers: Integer;
    BestScore: Integer;
    subtype CandidateArray is array(VoterArray_Index) of Integer;
    Candidate: CandidateArray;

    begin
        for I in CandidatesArray_Index loop
            Candidate := Candidates(I);
            for J in VoterArray_Index loop
                if Candidate(J) /= 0 and Voter(J) /= 0 then
                    if Candidate(J) /= Voter(J) then
                                     DifferentAnswers                    :=                    DifferentAnswers + 1
                    else
                        SameAnswers := SameAnswers + 1
                    end if;
                end if;
            end loop;
            if SameAnswers - DifferentAnswers >= BestScore then
                Best_Candidates(I) := Candidate;
            end if;
            SameAnswers := 0;
            DifferentAnswers := 0;
        end loop;
    end Get_Best_Score;

正如您所看到的，我不确定如何获取数字并将它们放入数组中。如果你有任何建议或不同的方式我应该做的事情，我都听见了。

提前致谢。

Answer 1

您可以使用流来读取数据： Integer'Read( STREAM_HANDLE, VARIABLE )

另一种选择是通过Get为数组的每个元素读取值，我建议使用辅助函数，以防需要调整处理格式更改的过程：

    Function  Get_Vote ( File  : File_Type ) Return Integer is
    begin
        Return Result : Integer do
            Integer_IO.Get(
                File  => File,
                Item  => Result
               );
        End return;
    end Read_Votes;

和

For Index in VOTE_ARRAY'range loop
    VOTE_ARRAY( Index ) := Get_Vote( INPUT_FILE );
End loop;

Answer 2

因为文件中给出了行数，所以constrained array必须足够大以容纳所有可能的元素。相反，您可以声明unconstrained array：

subtype Voter_Index is Positive range 1 .. 10;
type Voter_Array is array(Voter_Index) of Integer;
type Candidate_Array is array(Character range <>) of Voter_Array;

稍后，当您知道实际计数时，您只能分配数组实际需要的空间。该声明将Candidates放在nested scope：

的堆栈中

Number_Of_Candidates := ...;
declare
   Candidates : Candidate_Array(
      'A' .. Character'Val(Character'Pos('A') + Number_Of_Candidates));
begin
   ...
end;

或者，你可以allocate space on the heap：

type Candidate_Array_Ptr is access Candidate_Array;
Candidates: Candidate_Array_Ptr;

begin
   Number_Of_Candidates := ...;
   Candidates := new Candidate_Array(
     'A' .. Character'Val(Character'Pos('A') + Number_Of_Candidates));
end;

在任何一种情况下，您都可以根据需要访问数组元素：

for i in Candidates'Range loop
   for j in Voter_Array'Range loop
      Ada.Integer_Text_IO.put(Candidates(i)(j), 5);
   end loop;
   Ada.Text_IO.New_Line;
end loop;

附录：此方法假设候选人姓名是连续的Character。作为替代方案，请考虑一个Candidate_Record数组，其中从文件中读取每个Name：

type Candidate_Record is
   record
      Name  : Character;
      Votes : Voter_Array;
   end record;
type Candidate_Array is array(Positive range <>) of Candidate_Record;

Candidates : Candidate_Array(1 .. Number_Of_Candidates);

for i in Candidates'Range loop
   Ada.Text_IO.Put(Candidates(i).Name & ':');
   for j in Voter_Array'Range loop
      Ada.Integer_Text_IO.Put(Candidates(i).Votes(j), 5);
   end loop;
   Ada.Text_IO.New_Line;
end loop;

坚持Ada程序 - 坚持投入

2 个答案: