Nested conditional operators?

Question

This seems stupid - must be me!

Say I had a string filter["size]" = "g1g" this actually reads "greater" "1" "gb"

so

I've done a test to see if "first" character is a character, and work out its greater I've done a test to see if "last" character is a character, and work out its gb, or mb, or whatever

first and last are both boolean.

I then set x (cos I was getting stroppy) to length of filter["size"] which is a string.

However, I've come to copy the final number(s) in the middle.

Int64.Parse(filter["size"].Substring(first?1:0,last?(first?x-2:x-1):x));

And it doesnt like the nested inline ifs..

Substring(first?1:0,last?(first?x-2:x-1)); complains that its missing the :, which is right, but the instant you add it it complains

Error   1   The best overloaded method match for 'string.Substring(int, int)' has some invalid arguments

Im beginning to think I should just have parsed it with regexpr, but now Im curious as to why this isnt working.

So, irrelevant of there could be a ton of better ways, can anyone tell me why these nested inline ifs dont work?

They're not "nested inline ifs" - they're conditional operators. It would also be easier to read your code if you'd include some whitespace... Now, as for the actual question - please show a short but complete program which demonstrates the problem. In particular, you haven't told us the type of x. — Jon Skeet
– Jon Skeet, Commented Oct 2, 2012 at 9:27
Nested ternary operators are an evil, unreadable mess. If you start thinking about using them, then break your code out in to if statements and multiple lines. You score points for clarity not extreme brevity. — Quentin
– Quentin, Commented Oct 2, 2012 at 9:28
You note (correctly) that you've missed the :, but then you don't explain what you add. For example, if you add : null then you'll get the error you describe. Post the rest of your code! — Dan Puzey
– Dan Puzey, Commented Oct 2, 2012 at 9:46
JonSkeet its an Int .. Dan yes I did.. thats the line that starts Int64.Parse - the second part is what I was trying to work out what it felt was wrong with it. — BugFinder
– BugFinder, Commented Oct 2, 2012 at 10:01
Nested ternary operators do work. You need to explain what x and first are (is x just an int, or a nullable int?). If you refactored your code out to multiple lines, you would be able to tell precisely which part of your code is the problem. — Dan Puzey
– Dan Puzey, Commented Oct 2, 2012 at 12:03

tomfanning · Accepted Answer · 2012-10-02 09:34:43Z

4

And it doesnt like the nested inline ifs..

The Conditional operator ?: is not complete in you Substring

I will break it down for you

Substring(
           first
               ? 1
               : 0,
           last 
               ? (first ? x-2 : x-1 )
               : [something]  // this is the bit you're missing
);

edited Oct 2, 2012 at 9:34

tomfanning

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answered Oct 2, 2012 at 9:30

HatSoft

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2 Comments

tomfanning Over a year ago

I edited this answer to make the structure more clear - but heed the comments - if I was asked to code review this, it would be thrown straight in the bin. Terribly unreadable, confusing, and no benefit to inlining these conditionals.

BugFinder Over a year ago

You missed the first line which was the complete line... So this isnt true

Dan Puzey · Accepted Answer · 2012-10-02 12:07:25Z

2

Your code is perfectly compilable as you've described it, if horrendously readable. Filling out your blanks, I tried this:

int x = 6;
bool first = false;
bool last = false;
var filter = new Dictionary<string, string>();
filter.Add("size", "12345697");
var result = Int64.Parse(filter["size"].Substring(first?1:0,last?(first?x-2:x-1):x));

This code results in result being set to 123456. No errors, no problems.

There is something wrong with your surrounding code; your ternary expressions are fine.

answered Oct 2, 2012 at 12:07

Dan Puzey

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1 Comment

BugFinder Over a year ago

Well now Im stumped. When I removed the line in my code, the rest was fine, it had no issues, in the end I dropped the last/first bools and just removed the character as it was found, and then parsed the rest.. However, I guess I will never find out what made it hate what I had. Thank you for proving my logic wasnt wrong, just something else was!

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