是什么导致此Ada编译错误“模糊字符文字”？ [英] What caused this Ada compilation error "ambiguous character literal"?

问题描述

我有这个Ada代码。

with Ada.Text_IO; 
use Ada.Text_IO;

procedure for_Loop is
begin
    for Counter in 'A'..'Z' loop
        Put(Counter);   
    end loop;
    New_Line;
end for_Loop;

Ada编译器（gnatmake）输出这些错误消息。

The Ada compiler (gnatmake) outputs these error message.

gcc -c for_loop.adb
for_loop.adb:6:24: ambiguous character literal
for_loop.adb:6:24: possible interpretation: Character
for_loop.adb:6:24: possible interpretation: Wide_Character
for_loop.adb:6:24: possible interpretation: Wide_Wide_Character
gnatmake: "for_loop.adb" compilation error

代码有什么问题？

推荐答案

来自此帖子：

问题在于'A'和'Z'可能来自Character或Wide_Character。最简单的修正是使类型明确。例如：对于字符范围为'A'的Char ..'Z'循环...结束循环；

The problem is that 'A' and 'Z' could be from either Character or Wide_Character. The simplest correction is to make the type explicit; e.g.: for Char in Character range 'A' .. 'Z' loop ... end loop;

with Ada.Text_IO; 
use Ada.Text_IO;

procedure for_Loop is
begin
    for Counter in Character range 'A'..'Z' loop
        Put(Counter);   
    end loop;
    New_Line;
end for_Loop;

这是赔率：

ABCDEFGHIJKLMNOPQRSTUVWXYZ

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