如何在Dart中使用char类型？ （打印字母表） [英] How to work with char types in Dart? (Print alphabet)

问题描述

我想学习 Dart语言

我们C池中的第一个练习是写一个函数 print_alphabet（）以小写打印字母;

The very first exercice in our C pool is to write a function print_alphabet() that prints the alphabet in lowercase; it is forbidden to print the alphabet directly.

在POSIX C中，直接的解决方案是：

In POSIX C, the straightforward solution would be:

#include <unistd.h>

void    print_alphabet(void)
{
    char    c;

    c = 'a';
    while (c <= 'z')
    {
        write(STDOUT_FILENO, &c, 1);
        c++;
    }
}

int     main(void)
{
    print_alphabet();
    return (0);
}

然而，据我所知，Dart的当前版本1）没有一个简单的方法来处理字符。我想出的最远的（对于我的第一个版本）是这样：

However, as far as I know, the current version of Dart (1.1.1) does not have an easy way of dealing with characters. The farthest I came up with (for my very first version) is this:

void  print_alphabet()
{
  var c = "a".codeUnits.first;
  var i = 0;

  while (++i <= 26)
  {
    print(c.toString());
    c++;
  }
}

void main() {
  print_alphabet();
}

将每个字符的ASCII值（97...122）。不是真正的我想要的...

Which prints the ASCII value of each character, one per line, as a string ("97" ... "122"). Not really what I intended…

我试图搜索一个正确的方法这样做。但是缺少像C中那样的 char 类型给我一个很难的时间，作为一个初学者！

I am trying to search for a proper way of doing this. But the lack of a char type like the one in C is giving me a bit of a hard time, as a beginner!

推荐答案

Dart没有字符类型。

Dart does not have character types.

要将代码点转换为字符串， c $ c> String 构造函数 String.fromCharCode ：

To convert a code point to a string, you use the String constructor String.fromCharCode:

int c = "a".codeUnitAt(0);
int end = "z".codeUnitAt(0);
while (c <= end) {
  print(new String.fromCharCode(c));
  c++;
}

对于这样的简单东西，我会使用print

For simple stuff like this, I'd use "print" instead of "stdout", if you don't mind the newlines.

还有：

int char_a = 'a'.codeUnitAt(0);
print(new String.fromCharCodes(new Iterable.generate(26, (x) => char_a + x)));

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