Ada中的字符串数组 [英] String Arrays in Ada

问题描述

我在Ada95中有一个程序，其中必须创建一个字符串数组。该数组可以包含长度可变的字符串。

I have a program in Ada95, in which I have to create an array of strings. This array can contain strings of variable length.

示例：
我声明了一个数组，其中所有索引都可以存储大小为50的字符串。当我分配时上面的数组中的一个较小的字符串，我得到约束错误。

Example: I have declared the array in which all the indexes can store strings of size 50. When I assign a smaller string to the above array, I get "Constraint Error".

代码：

procedure anyname is
    input_array : array(1..5) of String(1..50);
begin
    input_array(1):="12345";
end anyname;

我尝试创建Unbounded_Strings数组。但这也不起作用。谁能告诉我如何在上面的字符串数组中存储这个 12345吗？

I have tried to create the array of Unbounded_Strings. But that doesn't work either. Can anyone tell me how to store this "12345" in the above string array?

推荐答案

如果您使用 Unbounded_String ，您不能直接为它分配字符串文字。字符串文字可以具有 String ， Wide_String 或 Wide_Wide_String 类型， 但没有别的;并且Ada中的分配通常要求目标和源的类型相同。要将 String 转换为 Unbounded_String ，需要调用 To_Unbounded_String 函数：

If you use Unbounded_String, you cannot assign a string literal to it directly. String literals can have type String, Wide_String, or Wide_Wide_String, but nothing else; and assignment in Ada usually requires that the destination and source be the same type. To convert a String to an Unbounded_String, you need to call the To_Unbounded_String function:

procedure anyname is
    input_array : array(1..5) of Ada.Strings.Unbounded.Unbounded_String;
begin
    input_array(1) := Ada.Strings.Unbounded.To_Unbounded_String ("12345");
end anyname;

您可以使用用法子句；其他一些程序员可能会定义自己的重命名功能，甚至可能使用一元 + 运算符：

You can shorten the name by using a use clause; some other programmers might define their own renaming function, possibly even using the unary "+" operator:

function "+" (Source : String) return Ada.Strings.Unbounded.Unbounded_String
    renames Ada.Strings.Unbounded.To_Unbounded_String;

procedure anyname is
    input_array : array(1..5) of Ada.Strings.Unbounded.Unbounded_String;
begin
    input_array(1) := +"12345";  -- uses renaming "+" operator
end anyname;

并不是每个人都喜欢这种风格。

Not everyone likes this style.

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