CString

speedy4711

Hi, is there an easy way (a function) to test if a CString contains only numbers? Thanks

Hamid Taebi

See

isdigit();

How to read your string?

_**

**_

WhiteSky

_AnsHUMAN_

speedy4711 wrote:

CString contains only numbers?

CString str="1142654";
int i=atoi (str);
CString str1;str1.Format("%d",i);
if(str.GetLength ()==str1.GetLength ())
	AfxMessageBox("string is pure number");
else 
	AfxMessageBox ("Characters exist");

Somethings seem HARD to do, until we know how to do them. ;-)_AnShUmAn_

_AnsHUMAN_

WhiteSky wrote:

atoi(m_Str);//return value is 0

If the string is as 12a3 then Index would be 12 and not 0 inspite of the fact that there exists a character in the third place.

Somethings seem HARD to do, until we know how to do them. ;-)_AnShUmAn_

kakan

CString m_Str; m_Str="123ABC"; Index=atoi(m_Str);//return value is 123 Gives 123 too, and m_Str doesn't contain only numbers...

Alcohol. The cause of, and the solution to, all of life's problems - Homer Simpson

Jorgen Sigvardsson

Here's a small function I use for validating user input:

bool IsNumeric(const CString& str)
{
if(str.IsEmpty())
return false;

for(int i = 0; i < str.GetLength(); i++)
	if(str\[i\] < '0' || str\[i\] > '9')
		return false;

return true;

}

It only takes decimal non-negative integers into account. It's easy to extend for other types of numbers, should you want to.

-- Mit viel Oktan und frei von Blei, eine Kraftstoff wie Benziiiiiiin!

_AnsHUMAN_

speedy4711 wrote:

test if a CString contains only numbers?

here's one more solution. You can give this a try...

CString s="253453";
CComVariant v;
v=s;
if(v.ChangeType(VT_INT)==S_OK)
{
	CString str;str.Format ("%d",v.intVal );
	AfxMessageBox (str);
}

Somethings seem HARD to do, until we know how to do them. ;-)_AnShUmAn_

KarstenK

I looked over the responses, and I want to point to two possible problems. The first may be a leading Zero ( "0123" ) and the other is a value with a comma or a sign ( "-1,5" or "+ 2.7" ) I would resolve this with checking every char of being a digit or allowed other char.

Greetings from Germany

SilentSilent

_AnShUmAn_ wrote:

if(str.GetLength ()==str1.GetLength ())

Doesn't work with eg. CString str="0x1142654";

SilentSilent

Jörgen Sigvardsson wrote:

for(int i = 0; i < str.GetLength(); i++) if(str[i] < '0' || str[i] > '9') return false;

Doesn't work with eg. CString str="0x1142654";

Jorgen Sigvardsson

How often do you accept hexadecimal user input? And how hard would it be to extend it? I never claimed it would recognize all possible numeric syntaxes...

-- Mit viel Oktan und frei von Blei, eine Kraftstoff wie Benziiiiiiin!

_AnsHUMAN_

SilentSilent wrote:

Doesn't work with eg.

Since this value you are entering is a string x is treated as a character only, it doesn't represent a hexadecimal number nor did I check for this.So I would try and provide a solution for this... Thanks for pointing this out...

Somethings seem HARD to do, until we know how to do them. ;-)_AnShUmAn_

David Crow

Why don't you just use strtol()?

"Talent without discipline is like an octopus on roller skates. There's plenty of movement, but you never know if it's going to be forward, backwards, or sideways." - H. Jackson Brown, Jr.

"Judge not by the eye but by the heart." - Native American Proverb

Zac Howland

Here is a base-10 checker that allows for ,'s and -'s (but doesn't check for placement). You can easily extend it to check for proper placement of special characters (,'s, and -'s) as well as other base numbers and floating point numbers.

// function to check for base-10 digits only
bool is_digit_base10(const CString& str)
{
	static CString allowedChars = _T("0123456789,-");
	const unsigned int length = str.GetLength();
	for (unsigned int i = 0; i < length; ++i)
	{
		char buffer[2] = {0};
		buffer[0] = str[i];
		if (-1 == allowedChars.FindOneOf(buffer))
		{
			return false;
		}
	}
	return true;
}

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac