今天发现了一个问题,即使数据库中的字段是空的,但是asp.net判断空值的时候是当它为一个空对象的。
例如以下片段:
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string phone = userinfo.Telephoe;
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if(phone != null)
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{
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string[] temp = phone.Split('-');
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//这里会报错
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}
![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/ExpandedBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedBlockEnd.gif)
所以,为了防止“未将对象的引用设置到对象的实例中”的异常的话,应该像这样判断:
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if(phone != null && phone.Length > 0)
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{
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}
![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/ExpandedBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedBlockEnd.gif)