How do I convert a CString to a float??

[Toe]

how can I convert a CString variable to a floating point?
(I'm using visuall c++ 6.0 and the MFC)

I'm trying to use an edit box to return a value which I'm putting into an array of floating points. I'm Using the GetWindowText method to get the value, which returns a CString. So I need to convert to a floating point. (or am I just doing things completely the wrong way?).

I presume there are methods for doing this already in the MFC.(have already used the Format method to convet to a CString display the values in the array in the edit box)

Thanks.

 

[Zyrenthian]

you can just do

CString pi = "3.14";
return atof(pi);

Matt

 

[sflam]

What you did is absolutely valid and I use that all the time. Reading a string value and parse/convert it to float allows you to locate the error when there is one. All you need is a help of a C Run-time function: strtod() or atof().

I would prefer strtod as the second argument returns a pointer to the string where the parse terminated:
CString str;
m_edtMyEditBox.GetWindowText(str);
char *pEnd;
double dValue = strtod(str.GetBuffer(str.GetLength()), &pEnd);
if (*pEnd != '\0')
{
// Error in parsing
}
str.ReleaseBuffer();


HTH
Shyan

 

[MinnisotaFreezing]

I am very glad you brought this up. When I write

CString string = "3.14";
float pi = 0.0f;
pi = atof(string);

I get the warning:

warning C4244: '=' : conversion from 'double' to 'float', possible loss of data

I have a project I am working on where I get this warning from this exact function atof() about 11 times. Strangly atof() returns a double, from MSDN

double atof( const char *string );

So my question is, should I go and change the doubles to floats, like I was planning, or doesn't it really matter? I don't like the warnings, and it really doesn't matter to me if I use a double or a float. A float is overkill already. (I'm storing dollar values).

Thanks guys

 

[VincentP]

you can cast the return value to float:

pi = (float)atof(string);

This will get rid of the warnings.

If you are storing dollar values, you might want to stores cents instead, so that you can use int or long instead.

Vincent

 

[MinnisotaFreezing]

Cool, thanks guys.

CJB