艾达（Ada）：在block语句中写入文件 [英] Ada: Writing to files within a block statement

问题描述

我正在处理一个数组，数组的长度是在程序执行期间确定的。因此，我使用了 block 语句，可以在其中设置数组的限制。

I am dealing with an array whose length is determined during the execution of the program. So I am making use of a block statement in which I can set the limits of the array.

我在使用存根进行写过程时遇到了将数组元素写到文件中的问题。我删除了存根以使所有内容都在同一代码中。尽管现在我的代码可以编译并运行，但它没有写入文件。这是代码：

I am having problems to write the elements of the array to a file as I was using a stub for the write procedure. I removed the stub to have everything in the same code. Though now my code compiles and run, it is not writing to the file. Here is the code:

with Ada.Float_Text_IO;
with Ada.Integer_Text_IO;
with Ada.Text_IO; 


procedure Compute_Parameters is

Spin_Speed, Whirling_Speed        : Float;
Time_Step, Rotor_Revolutions      : Float;
Number_Of_Steps                   : Float;


begin
Ada.Text_IO.Put("Enter the spin speed ");
Ada.Float_Text_IO.Get (Item => Spin_Speed);
Ada.Text_IO.New_Line (1);
Ada.Text_IO.Put("Enter the whirling speed ");
Ada.Float_Text_IO.Get (Item => Whirling_Speed);
Ada.Text_IO.New_Line (1);
Ada.Text_IO.Put("Enter the time step ");
Ada.Float_Text_IO.Get (Item => Time_Step);
Ada.Text_IO.New_Line (1);
Ada.Text_IO.Put("Enter the number of revolutions of the rotor ");
Ada.Float_Text_IO.Get (Item => Rotor_Revolutions);


Number_Of_Steps := (360.0 / (Time_Step * Whirling_Speed)) * Rotor_Revolutions *  (Whirling_Speed / Spin_Speed);


declare

   type Vector is array (Integer range <>) of Float;
   Time_Vector                     : Vector (1 .. Integer (Float'Truncation (Number_Of_Steps)) + 1);
   Rotor_Position_Degrees          : Vector (1 .. Integer (Float'Truncation (Number_Of_Steps)) + 1);

   Count       : Integer := 0;
   Start       : Float := 0.0;
   Step        : Float := Time_Step;

   Output_Data_File                            : File_Type;

   procedure Write_Files (Output_File          : File_Type;
                          Out_1                   : Integer;
                          Out_2                   : Float;
                          Prec                    : Natural := 5
                          ) is 
   begin
      Ada.Integer_Text_IO.Put (File => Output_File, Item => Out_1);
      Ada.Text_IO.Put (Output_File, "   ");
      Ada.Float_Text_IO.Put (File => Output_File, Item => Out_2, Fore => 6, Aft => Prec, Exp => 0);
      Ada.Text_IO.New_Line (Output_File);
   end Write_Files;



 begin -- begin of Declare

     Ada.Text_IO.Put ("Put file name to write: ");
     Create (Output_Data_File, Out_File, Get_Line);


     for I in 1 .. Time_Vector'Length  loop
         Count := Count + 1;
         Time_Vector(I) := Start + Step * Float(I-1);
         Put (Integer'Image(Count));
         Ada.Text_IO.Put("   ");
         Rotor_Position_Degrees(I) := Spin_Speed * Time_Step * Float(I-1);
         Ada.Float_Text_IO.Put (Item => Rotor_Position_Degrees(I), Fore => 5, Aft  => 1, Exp  => 0);
         Ada.Text_IO.New_Line(1);

         --write to file
         Write_Files (Output_Data_File,
                      Out_1 => Count,
                      Out_2 => Rotor_Position_Degrees(I)
                      );
     end loop;

 close(Output_Data_File);


 end; -- end of Declare


end Compute_Parameters;

我注意到之后的两行声明中的>根本没有执行：

I notice that the 2 lines just after begin in Declare are not being executed at all:

Ada.Text_IO.Put ("Put file name to write: ");
Create (Output_Data_File, Out_File, Get_Line);

我在做什么错了？

谢谢...

推荐答案

在最后一个获取之后，按回车键 Rotor_Revolutions 在标准输入中留空行，有待阅读：

Pressing return after your last Get for Rotor_Revolutions has left an empty line in standard input, which remains to be read:

 Ada.Text_IO.Put_Line (Ada.Text_IO.Get_Line);
 Ada.Text_IO.Put ("Put file name to write: ");
 Create (Output_Data_File, Out_File, Ada.Text_IO.Get_Line);

只需澄清一下：这是 Get_Line 需要; Put_Line 只是为了表明它是空行。

Just to clarify: It's the Get_Line that's required; the Put_Line is just to show that it's an empty line.

或者，使用 Ada.Command_Line ，如此示例所示。

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