This situation has always nagged me. Just as an example, suppose a console application expects filepath in as a command line argument.
string first = args[0];
but if there are no arguments, then an error will occur. I suppose I could do something like the following:
string first = (args[0]!=null) ? args[0] : "c:\";
What I'm looking for is something a bit more elegant like:
string first = (MyTryParse(args[0],"c:\");
Which I could write as an extension, however that won't work because args[0] will throw an exception before the method can be called.
Also check, if args[0]
is null:
public string MyTryParse(string[] args, int index, string defaultVal)
{
return index < args.Length ? (args[index] ?? defaultVal) : defaultVal
}
...
string first = MyTryParse(args, 0, "c:\");
Pass args
instead of args[0]
Try like this
public string MyTryParse(string[] args, string defaultVal) {
return args.Length > 0 ? args[0] : defaultVal
}
Same approach but using extension
method,
public static class Extensioin
{
public static string MyTryParse(this string[] args, string defaultVal)
{
return args.Length > 0 ? args[0] : defaultVal;
}
}
And using above method something like this,
string first = args.MyTryParse(@"c:\");
LINQ为此已经具有DefaultIfEmpty
方法:
string first = args.DefaultIfEmpty("c:\\").First();
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