英文:
Undefine a constant in Visual Basic
问题
In C#, conditional compilation symbols can be undefined (removed) with:
#undef SYMBOL_1
// ...
#if SYMBOL_1
ThisDoesNotRun();
#else
ButThisDoesRun();
#endif
Visual Basic has something similar called "Constants":
#Const VB_SYMBOL_1 = True
' ...
#If VB_SYMBOL_1
ThisWillRun()
#End If
#If Not VB_SYMBOL_1
ButThisWillNot()
#End If
Visual Basic does not have a direct equivalent of #undef in C#. You can redefine the constant with #Const VB_SYMBOL_1 = False, but this is not the same thing.
英文:
In C#, conditional compilation symbols can be undefined (removed) with:
#undef SYMBOL_1
// ...
#if SYMBOL_1
ThisDoesNotRun();
#else
ButThisDoesRun();
#endif
Visual Basic has something similar called "Constants":
#Const VB_SYMBOL_1 = True
' ...
#If VB_SYMBOL_1
ThisWillRun()
#End If
#If Not VB_SYMBOL_1
ButThisWillNot()
#End If
Does VB have functionality to undefine a constant, like undef in C#?
You can redefine the constant with #Const VB_SYMBOL_1 = False, but this is not the same thing.
答案1
得分: 0
这个答案来自对问题的评论（感谢 Hans）。要取消定义预处理器常量，请使用：
#Const VB_SYMBOL_1 = Nothing
英文:
This answer is from a comment to the question (thanks Hans). To undefine a preprocessor constant use:
#Const VB_SYMBOL_1 = Nothing
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