> For the complete documentation index, see [llms.txt](https://beej-c-zhtw.netdpi.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://beej-c-zhtw.netdpi.net/3.-bian-shu-yu-chen-shu-shi/3.1.-bian-shu/3.1.1.variable-name.md).

# 3.1.1. 變數名稱

您可以使用範圍在 0-9、A-Z、a-z 之間與底線的任何字元作為變數名稱，規則如下：

* 變數開頭不能是數字0-9。
* 變數名稱的開頭不能是兩個底線。
* 變數名稱的開頭不能是底線加上大寫字母A-Z。

如果是 Unicode（萬國碼），請試試看。在§D.2的規格中，有一些規則會討論 Unicode 中哪些部分允許使用哪些 Unicode 的字碼點（codepoint）範圍，但是這裡寫不完，說不定你可能永遠都不會想要用到。


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