Check for characters

[aewarnick]

This causes a fatal error if the input is not a number.

if ((float.Parse(x.Text) >- 1)||(float.Parse(x.Text) < 9999999))

How do I stop the the conversion if the user enters in a character?

How do I check to see if what was entered was a character or number?

[Jeremy Martin]

Throw a textBox on a form called textBox1 and give this a try.

string outputStr = "";
            foreach(char myChar in textBox1.Text)
            {
                if(Char.IsNumber(myChar))
                {
                    outputStr += myChar.ToString();
                }
            }
            textBox1.Text = outputStr;
            textBox1.Select(textBox1.Text.Length, textBox1.Text.Length +1); 

Jeremy

[DevGrp]

Put the above in a try catch block.

[sunburnt]

Just off the top of my head, wouldn't that cause a problem if the user entered a decimal number?

[aewarnick]

I'll have to give that a try and experimentation to see how it works.

[aewarnick]

I Like that!!! It is something I was looking for anyways.

[aewarnick]

I figured out a way around the . bug:

if(!Char.IsSymbol(myChar)&&(!Char.IsLetter(myChar)))

[aewarnick]

But I can't get rid of the spaces. Any ideas?

[sunburnt]

string outputStr = "";
bool bFoundDecimal = false;

            foreach(char myChar in textBox1.Text)
            {
                if(Char.IsNumber(myChar))
                {
                    outputStr += myChar.ToString();
                }
                else if ((!bFoundDecimal) && (myChar == '.'))
                {
                    // there can only be one decimal!
                    outputStr += myChar.ToString();
                    bFoundDecimal = true;
                }
            }
            textBox1.Text = outputStr;
            textBox1.Select(textBox1.Text.Length, textBox1.Text.Length +1); 

[aewarnick]

So I can substitute this

(myChar == '.')

with this

(myChar == ' ')

to get rid of the spaces and I won't forget to omit the bool for that.

Right?

[Jeremy Martin]

That should work.

Jeremy

[aewarnick]

Good! Will that work even if the user uses tabs instead of spaces. Or are tabs==spaces.

[Jeremy Martin]

i do not think that tabs are spaces think that tabs are '\t' characters.

Jeremy

[aewarnick]

You may be right. But I hope that tabs are evaluated as one space at a time.

[White Rose]

In C#, how to determine if the string is a number or not?

[CornedBee]

What kind of number?

[White Rose]

any.
i'm writting a program which highlight source code. because i want to check if the string is a number to mark it.
some examples:
3
3.12

[CornedBee]

What about hexadecimal?

bool isNumber(string str)
{
  bool ret = str.Length > 0;
  int hasPoint = 0;
  foreach(char c in str) {
    ret = ret && (char.IsDigit(c) || (c == '.' && hasPoint++ == 0));
  }
  return ret;
}

Note that this will fail if your string contains more than 2^32 '.'