If you attempt to use an undeclared variable name, an error occurs at compile time.

如果您尝试使用未宣告的变数名称，会发生编译时期错误。

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If you attempt to use an undeclared variable name, an error occurs at compile time.

如果您尝试使用未宣告的变数名称，会发生编译时期错误。

youdao