Snobol4 语言实战：半角标点转换实战

Snobol4 是一种古老的编程语言，它以其简洁的语法和强大的字符串处理能力而闻名。我们将通过一个实战案例——半角标点转换，来展示如何使用 Snobol4 语言进行字符串处理。半角标点转换是指将全角标点符号转换为半角标点符号的过程，这在处理中文字符串时尤其有用。

Snobol4 简介

Snobol4 是 Snobol（StriNg OBjects and Symbols）语言的第四个版本，它由David J. Farber和Ralph E. Griswold于1962年设计。Snobol4 专注于字符串处理，具有丰富的字符串操作函数，非常适合于文本处理任务。

Snobol4 的语法相对简单，它使用一系列的规则和模式来匹配和操作字符串。以下是一些基本的 Snobol4 语法元素：

- 模式：用于匹配字符串的模式，如 ``（匹配任意字符）、`?`（匹配任意字符0次或1次）等。
- 规则：用于定义如何处理匹配到的字符串的模式。
- 变量：用于存储数据的标识符。

半角标点转换实战

1. 确定半角和全角标点符号

在开始编写代码之前，我们需要明确半角和全角标点符号的对应关系。以下是一些常见的半角和全角标点符号：

- 全角句号：。
- 半角句号：。
- 全角逗号：，
- 半角逗号：，
- 全角引号：“”
- 半角引号：""

2. 编写 Snobol4 代码

以下是一个 Snobol4 程序，用于将输入的全角标点符号转换为半角标点符号：

```snobol
:input
input:in
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