问题
Possible Duplicate:
How to check if String is null
I need to be able to check for a null value, only, inside a string. The best method I am currently aware of is String.IsNullOrEmpty(), which does not fit what we are trying to do (string.empty values are allowed, nulls are not). Does anyone have any suggestions?
回答1:
just compare your string to null
bool stringIsNull = mystring == null;
here's an extension method for you
public static class ExtensionMethods
{
public static bool IsNull(this string str)
{
return str == null;
}
}
回答2:
You check the same way you check if any other variable is null:
if(variable == null)
{
//do stuff
}
回答3:
If you want to skip null values, simply use != null:
if(str != null)
{
}
回答4:
if (variable != null)
//do your action for not null
else
//variable is null
来源：https://stackoverflow.com/questions/14204782/best-c-sharp-method-for-checking-for-a-null-string-value