Check String null or empty and replace with another string

Question

In here i want to, If AvailCode comes as a null or empty string then i need to show it "Temporary Unavailable".But my coding doen't show that one. (Consider only Avail Code).

var _staff = trv.GetBookDetails("4500").Select(b => new
{
    value = b.bookno,
    text =  b.bookname + " " + "/"+" " + b.AvailCode ?? "TemporaryUnavailable",  
});

text = String.Format("{0} / {1}", b.bookname, String.IsNullOrEmpty(b.AvailCode) ? "TemporaryUnavailable" : b.AvailCode); — Dmitrii Bychenko
– Dmitrii Bychenko, Commented Feb 2, 2016 at 7:01

fubo · Accepted Answer · 2016-02-02 07:11:57Z

6

the ?? operator only handles the NULL case, not the empty case

replace

b.AvailCode ?? "TemporaryUnavailable"

with

string.IsNullOrEmpty(b.AvailCode)? "TemporaryUnavailable" : b.AvailCode

so the correct line would be

text = b.bookname + " / " + (string.IsNullOrEmpty(b.AvailCode) ? "TemporaryUnavailable" : b.AvailCode),

edited Feb 2, 2016 at 7:11

answered Feb 2, 2016 at 6:58

fubo

46.2k20 gold badges109 silver badges139 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

TechGuy Over a year ago

It shows me the error "Cannot implycitly convert type bool to string"

Irshad · Accepted Answer · 2016-02-02 06:58:22Z

2

?? operator which called null-coalescing operator returns the left-hand operand if the operand is not null; otherwise it returns the right hand operand.

This won't check for empty;

Use string.IsNullOrWhitespace method instead.

string.IsNullOrWhitespace(b.AvailCode) ? "TemporaryUnavailable" : b.AvailCode

answered Feb 2, 2016 at 6:58

Irshad

3,1415 gold badges33 silver badges57 bronze badges

Comments

Zbynek Vyskovsky - kvr000 · Accepted Answer · 2016-02-02 07:07:08Z

1

Operator ?? has very low precedence, it's evaluated after the + operators on the left side. Therefore you can never really get null on the left side. You need to wrap into parenthesis:

  text =  b.bookname + " " + "/"+" " + (b.AvailCode ?? "TemporaryUnavailable"),

or, in case you want to handle also empty:

  text =  b.bookname + " " + "/"+" " + (string.IsNullOrEmpty(b.AvailCode) ? "TemporaryUnavailable" : b.AvailCode),

answered Feb 2, 2016 at 7:07

Zbynek Vyskovsky - kvr000

19.1k3 gold badges41 silver badges49 bronze badges

Collectives™ on Stack Overflow

Check String null or empty and replace with another string

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related