CODEWITHSUNDEEP
c#winforms
ghost_king
ghost_king

Reputation: 930

Checking a TextBox for an empty string, an integer or a string

I am checking a text box for the following

The code -

if (this.BugCompPct.Text == String.Empty)      
else if (Convert.ToInt32(this.BugCompPct.Text) > 100 | Convert.ToInt32(this.BugCompPct.Text) < 0)
//Not sure about checking the last if

What could I put as the if conditional to check for a string other than an integer? I want only the input to be an integer and nothing else

Thanks

Upvotes: 0

Views: 18605

Answers (4)

Habib
Habib

Reputation: 223267

What could I put as the if conditional to check for a string other than an integer?

Use int.TryParse method to see if the parsing is succesfull.

For empty string use string.IsNullOrWhiteSpace (supported on .Net framework 4.0 and later), For .Net framework 3.5 or lower you can use string.IsNullOrEmpty with string.Trim

Your check will all the conditions could be like:

if (!string.IsNullOrWhiteSpace(BugCompPct.Text))
{
    int temp; 
    if(int.TryParse(BugCompPct.Text,out temp)
    {
        if(temp >= 0 && temp <= 100)
        {
            //valid number (int)
        }
        else
        {
            //invalid number (int)
        }
    }
    else
    {
        //Entered text is not a number (int)
    }
}
else
{
    //string is empty
}

Upvotes: 3

Ehsan
Ehsan

Reputation: 32681

If you are on windows form you should use masked textbox.

Upvotes: 1

Philip Gullick
Philip Gullick

Reputation: 995

every value put into a textbox is as string. I would then advise you to tryparse rather than convert.to. (Why? tryparse can be handled much easier and won't crash and burn if there are bad values put into it)

just use int.TryParse(txtbox1.text, out i)

You must define integer i above this

then you can use if statements using i (the integer version) to validate it.

To check if its an integer only just use:

if(!int.TryParse(txtbox1.text, out i))
{
    // do work
}

then you can use > < in if statements to check how big the number is.

Upvotes: 1

gzaxx
gzaxx

Reputation: 17600

First check if TextBox is empty, then if string is valid number and last check boundaries.

int number = 0;

if (string.IsNullOrEmpty(this.BugCompPct.Text)
{
    //not valid
}
else if (Int32.TryParse(this.BugCompPct.Text, out number))
{
    if (number > 0 && number < 100)
    {
       //valid
    }
}

Upvotes: 1

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