问题描述
**我希望我的代码显示针对人口的下表，但似乎我的代码不是 甚至接近这个。那么如何正确编写代码？我最大的问题是使用基于范围的 for循环。该表显示了A和B的人口及其人口增长（百分比）， 要求用户输入一些数据，当总体b绕过总体a时，循环应 停。示例代码：**
Enter start year: 1976
Enter country A's population (in million): 200
Enter country A's population increase (in%): 10.0
Enter country B population (in million): 100
Enter country B population increase (in%): 50.0
Year Increase A Population A Increase B Population B
1976 ---- 200.00 ------ 100.00
1977 20.00 220.00 50.00 150.00
1978 22.00 242.00 75.00 225.00
1979 24.20 266.20 112.50 337.50
In 1979,country B bypassed country A in population.
我的代码：
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
procedure Population is
x,Population_A,Population_B:Float;
Growth_A,Growth_B,Growth_1,Growth_2: Float;
begin
Put("Write in the year: "); Get(x);
Put("Population_A: "); Get(Population_A);
Put("Population_B: "); Get(Population_B);
Put("Population grow for A: "); Get(Growth_A);
Put("Population growth for B: "); Get(Growth_B); New_Line;
Put("Year Growth A Population A Growth B Population B ");
for I in 1900..2018 loop
Put(Integer(I)); New_Line;
while Population_B < Population_A loop
Growth_1 := Growth_A +1.0;
Growth_2 := Growth_B +1.0;
Put(Growth_1,13,2,0); New_Line;
Put(Population_A + (Population_A * Growth_A/100.0),15,0); New_Line;
Put(Growth_2,17,0); New_Line;
Put(Population_B + (Population_B * Growth_B/100.0),19,0);
end loop;
end loop;
end Population;
解决方法
您的问题确实是在使用基于范围的for循环。还有其他形式。
我可能会选择
-- read in the data
-- check that there is actually a solution
-- (B’s population not already greater than A’s)
Year := -- value read from data,e.g. 1976
loop
Year := Year + 1;
Population_Of_A := -- calculate it
Population_Of_B := -- calculate it
exit when Population_Of_B > Population_Of_A;
end loop;
您需要对要解决的问题有更完整的了解。
该问题假设每个国家的人口增长率恒定。尽管此假设简化了问题，但远非现实。
A国或B国都可以从较小的初始人口开始。如果从人口较少的国家开始，人口增长率也最低，那么人口较小的国家将永远不会超过人口大的国家。您的计划将如何处理这两个国家最初可能会有更多人口的可能性？
以下程序处理其中一些问题，但并非全部。通过研究以下程序，也许您可以了解如何解决所有问题。
with Ada.Text_Io; use Ada.Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Main is
Year : Positive;
type Country (Id : Character) is record
Population : Float;
Rate : Float;
Increase : Float;
end record;
type Country_Access is access all Country;
Country_A : aliased Country('A');
Country_B : Aliased Country('B');
Smaller : Country_Access;
Larger : Country_Access;
procedure Display(Yr : Positive; Cnt_A : Country; Cnt_B : Country) is
begin
Put(Item => Yr,Width => 4);
Put(Item => Cnt_A.Increase,Aft => 2,Fore => 8,Exp => 0);
Put(Item => Cnt_A.Population,Exp => 0);
Put(Item => Cnt_B.Increase,Exp => 0);
Put(Item => Cnt_B.Population,Exp => 0);
New_Line;
end Display;
begin
Put("Enter start year: ");
Get(Year);
Put("Enter country A's population (in million): ");
Get(Country_A.Population);
Put("Enter country A's population increase (in %): ");
get(Country_A.Rate);
Country_A.Rate := (Country_A.Rate / 100.0);
Put("Enter country B's population (in million): ");
Get(Country_B.Population);
Put("Enter country B's population increase (in %): ");
Get(Country_B.Rate);
Country_B.Rate := (Country_B.Rate / 100.0);
if Country_A.Population < Country_B.Population then
Smaller := Country_A'Access;
Larger := Country_B'Access;
else
Smaller := Country_B'Access;
Larger := Country_A'Access;
end if;
Put_Line("Year Increase A Population A Increase B Population B");
Put(Item => Year,Width => 4);
Put(" ----------");
Put(Item => Country_A.Population,Exp => 0);
Put(" ----------");
Put(Item => Country_B.Population,Exp => 0);
New_Line;
while Smaller.Population <= Larger.Population loop
Year := Year + 1;
Country_A.Increase := Country_A.Population * Country_A.Rate;
Country_A.Population := Country_A.Population + Country_A.Increase;
Country_B.Increase := Country_B.Population * Country_B.Rate;
Country_B.Population := Country_B.Population + Country_B.Increase;
Display(Yr => Year,Cnt_A => Country_A,Cnt_B => Country_B);
end loop;
Put_Line("In" & Year'Image & " country " & Smaller.Id &
" bypassed country " &
Larger.Id & " in population.");
end Main;
编辑： 以下是上述程序的不使用访问类型的版本。
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure No_Access is
Year : Positive;
type Country is record
Population : Float;
Rate : Float;
Increase : Float;
end record;
Country_A : Country;
Country_B : Country;
procedure Increase
(Yr : in out Positive; A : in out Country; B : in out Country)
is
begin
Yr := Yr + 1;
A.Increase := A.Population * A.Rate;
A.Population := A.Population + A.Increase;
B.Increase := B.Population * B.Rate;
B.Population := B.Population + B.Increase;
Put (Item => Yr,Width => 4);
Put (Item => A.Increase,Exp => 0);
Put (Item => A.Population,Exp => 0);
Put (Item => B.Increase,Exp => 0);
Put (Item => B.Population,Exp => 0);
New_Line;
end Increase;
begin
Put ("Enter start year: ");
Get (Year);
Put ("Enter country A's population (in million): ");
Get (Country_A.Population);
Put ("Enter country A's population increase (in %): ");
Get (Country_A.Rate);
Country_A.Rate := (Country_A.Rate / 100.0);
Put ("Enter country B's population (in million): ");
Get (Country_B.Population);
Put ("Enter country B's population increase (in %): ");
Get (Country_B.Rate);
Country_B.Rate := (Country_B.Rate / 100.0);
Put_Line ("Year Increase A Population A Increase B Population B");
Put (Item => Year,Width => 4);
Put (" ----------");
Put (Item => Country_A.Population,Exp => 0);
Put (" ----------");
Put (Item => Country_B.Population,Exp => 0);
New_Line;
if Country_A.Population < Country_B.Population then
while Country_A.Population <= Country_B.Population loop
Increase (Year,Country_A,Country_B);
end loop;
Put_Line
("In" & Year'Image & " country A bypassed country B in population.");
else
while Country_B.Population <= Country_A.Population loop
Increase (Year,Country_B);
end loop;
Put_Line
("In" & Year'Image & " country B bypassed country A in population.");
end if;
end No_Access;
设置时间 控制面板
错误1：Request method ‘DELETE‘ not supported 错误还原：...