Error cs0019 operator cannot be applied to operands of type string and string

Line 80:     {
Line 81:         
Line 82:             if ((TextBoxVoornaam.Text = "") || (TextBoxFamilienaam.Text = ""))
Line 83:             {
Line 84:                 LabelError.Text = "U dient alle velden in te vullen";

The operator || as well as | cannot be applied to string objects. It is a comparison operator for boolean types.

You can use this operator in expressions like this:

if ( string1 != string.Empty || string2 != string.Empty)

{

}

Your problem is that instead of boolean == you are using assignment operator =.

Change it into:

if ((TextBoxVoornaam.Text == «») || (TextBoxFamilienaam.Text == «»))

Line 80:     {
Line 81:         
Line 82:             if ((TextBoxVoornaam.Text = "") || (TextBoxFamilienaam.Text = ""))
Line 83:             {
Line 84:                 LabelError.Text = "U dient alle velden in te vullen";

The operator || as well as | cannot be applied to string objects. It is a comparison operator for boolean types.

You can use this operator in expressions like this:

if ( string1 != string.Empty || string2 != string.Empty)

{

}

Your problem is that instead of boolean == you are using assignment operator =.

Change it into:

if ((TextBoxVoornaam.Text == «») || (TextBoxFamilienaam.Text == «»))

Line 80:     {
Line 81:         
Line 82:             if ((TextBoxVoornaam.Text = "") || (TextBoxFamilienaam.Text = ""))
Line 83:             {
Line 84:                 LabelError.Text = "U dient alle velden in te vullen";

Done.

UnDone.

To continue from Alex’s post and add an improvement in the condition checks. This is how your code should look like:

Thanks, Rudedog, it was not quite rude of you

My problem is that I am not in competition for a job, or MVP title, or anything of this nature. I am not in a career track. Aquiring stars actually makes me rather antsy, they have an opposite effect. I want clarity and knowledge for my own sake and with growing «stardom» I feel that I still know very little as compared to many other people and feel less comfortable posting. It is a nonlinear rewared system.

I would appreciate if you actually delete that post.

Thanks.

Hi Bob, I think there might be a little problem in here. I mean in general so to speak. Let’s assume that he gets his string from an rtf file and it has two characrers in front: tn or whatever and nothing more.

There is a chance that the length of this string will be 2 and the string still be «empty» string.Empty == true; because they are WhiteSpace characters.

Look:

string str = string.Empty;

str += ‘n’;

str += ‘t’;

Console.WriteLine ( str.Length.ToString ( ) + » « + string.Compare ( str, string.Empty ).ToString ( ) );

Console.WriteLine ( str.Length.ToString ( ) + » « + str.CompareTo ( string.Empty ).ToString ( ) )

The result was

2 1

2 1

Obviously 1 means they are equal.

I don’t know what he actuall want, though with this statement.

Not in any sort of competition either.  Just helping folks find answers, and like you learning stuff along the way.

Thanks you and I appreciate your comment. It makes me feel I am not alone.

This thread has pretty much run out of life.  Check out the dates.

Mark the best replies as answers. «Fooling computers since 1971.»

if (answer.Text == option1.Text || answer.Text == option2.Text || answer.Text == option3.Text || answer.Text == option4.Text)

this is how we should do or else u will get an error u mentioned above