Win form [textbox] C#

Question

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Hi,

I want to make an interpreter but i´m having some problems with code.

Interpreter have to interpret when the user declares a var and recognize that the user want to declare a var.

Example:

user writes in the text-box2 -- "y = 2", or "r = 2"

I want that the interpreter create a variable with the value(string) given by user and assign the value(int, float, etc) given by user.

I have this code but it didn´t work:

C#

private void button1_Click(object sender, EventArgs e)
        {
            string in1 = textBox2.Text;
            string in2 = textBox2.Text;
            float conv;
            if (textBox2.Text == String.Format("{0} = {1}", in1, in2))
            {
                in1 = in2;
                conv = Convert.ToInt32(in2);
                textBox1.Text = String.Format("{0} = {1}", in1, in2);
            }

        }

and then the value of var (example: y") appears in the text-box1

example : text-box2 user writes -- "y = 3"

then, in text-box1 will appear this: "var created: y = 3"

I wonder if anyone can help me on this. :)

Posted 30-Sep-13 9:18am

Member 10303886

Updated 30-Sep-13 9:24am

v4

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Comments

idenizeni 30-Sep-13 15:43pm

There are many things wrong here. Why are you doing this, may be there is a better approach to what you are trying to do.

If you expect 'y = 2' as input then your if condition will always be false as you would be trying to match 'y = 2' against 'y = 2 = y = 2', which clearly do not match.

Also, the line...
conv = Convert.ToInt32(in2);
would generate an error as 'y = 2' would not convert to a float. You would need to parse out the number and only pass it to the ToInt32() function.

MCY 30-Sep-13 17:04pm

You should note that by this approach (correcting the mistakes in the comment before this one, of course), only strings you could parse would be simple equities such as x = a.

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Sergey Alexandrovich Kryukov · Accepted Answer · 2013-09-30T11:41:00

The code which reads two variables from text boxes is not an interpreter. You did not explain how it should work and why.
But your code makes no sense, as it looks like you mixed up variable name, string representations of the number (in your case, immediate constants declared in your input language, and the values themselves.

Let's see. If in.Text contains something like "x = 3", you should first parse it into "x" and "3", and check if "=" is really the assignment operator. Anyway, comparing in1 and in2 does not give you anything at all. Why would the user enter two identical strings in two different text boxes? But in your code, this is the main case. Besides, why getting textBox2.Text again, if you already got in2? And next statement in1 = in2; simply makes an assignment which looses previous value of in2. Why doing that if you have in2.

Overall, the impression is that you are not ready to write any interpreter, not even any UI. Please understand, I'm not trying to hurt you, I'm trying to give you a useful practical advice. You first need to gain some understanding and experience solving simple problems, better by writing simple console-only applications and reading documentation.

—SA