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struct point3D
{
double x;
double y;
double z;
};
std::vector<point3D> my_vector_of_points;
?
bool sortOnX(const point3D& a, const point3D& b)
{
return a.x < b.x;
}
std::sort(my_vector_of_points.begin(), my_vector_of_points.end(), sortOnX)
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Hi,
How could I change the
CMFCPropertyGridCtrl Property or Value column width?
a sample code would be more useful
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somehow late, but here you are:
class CMyPropertyGridCtrl : public CMFCPropertyGridCtrl
{
public:
int SetFirstColumn(int iwidth){ m_nLeftColumnWidth = iwidth;
AdjustLayout();return 0;};
};
...
{
...
CMyPropertyGridCtrl blah;
int iwidth;
blah.SetFirstColumn(iwidth);
...
}
...
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failed 
Best Regards
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Hi,
Does anyone know of a class in c++ or a workaround to the following problem when using the atof function?
I'm reading strings of values from an input file, then parsing the string into several substrings.
Then I take the substrings and attempt to convert them to doubles using atof. It works great most of the time, but everynow and then the atof function can't exactly represent a value and you may get "9.199999999999999" instead of the exact value in the string which is "9.2", or "0.5520000000000001" instead of "0.552".
Also, I can't just set the precision because some of the substrings may contain integers or doubles with a varying number of decimal places (ex. "9" or "9.321").
Any ideas?
Thanks,
modified on Friday, March 19, 2010 10:14 AM
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real numbers stored in binary are an approximation of strings represented in decimal, or vice versa; your system cannot easily represent 2/3 nor 1/10 accurately. The best you can do is:
- convert strings to reals, and live with the outcome;
- perform real operations on them;
- output to decimal strings with a specified precision.
And of course, if logic dictates (e.g. rounding rules in finance) use a rounding function.
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Hi ,
I had developed one MSI for my application. In this MSI, I add custom action by calling EXE to display message. When I run this MSI , my custom message is pop up before the Close button of last screen.But I want to show message after user click on Close button of last screen.
If any body know regarding this, please reply to me.
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You must put the EXE as a custom action appearing after the "setup complete" dialog.
How did you develop the MSI, what application did you use?
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struct myStruct {
int x;
int y;
char ch[10];
};
struct myOtherStruct {
int y;
char ch[10];
int x;
};
class myClass {
public:
myClass() { };
~myClass() { };
void someMethod(int x) { ; };
private:
int a;
int b;
char ch[10];
};
int main() {
myStruct s1;
myOtherStruct s2;
myClass c;
return 0;
};
Given these struct/class definitions, is it always safe to assume:
<br />
&s1.x < &s1.y < &s1.ch<br />
&s2.y < &s2.ch < &s2.x<br />
&c.a < &c.b < &c.ch<br />
(Considering the addresses as numbers, like you'd get from (__int64)&s1.x)
Maybe an easier way to ask this is, "Is the order of the members in memory the same as the order in which they are declared?"
Thanks in advance for any help you guys can offer!
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Yes, AFAIK.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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Mike the Red wrote: Is the order of the members in memory the same as the order in which they are declared?
No, absolutely not. Without additional information, any compiler can do as it pleases, as long as it is consistent. Here are two typical approaches:
1. reorder the items according to element size, possibly reducing struct size: since items want to be "naturally aligned" (i.e. a N-byte quantity starts at an address that is a multiple of N for best performance) it may pay off to put the largest ones first.
2. keep the declaration order and pad with dummy bytes to achieve natural alignment.
Not a single strategy is good for all purposes as one may want compatibility with another language, an existing data structure in a file, a set of registers in a hardware device, etc.
Hence, most compilers have switches and/or pragma's to control the exact behavior. You should read the documentation of your tools.
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C++ standard says that ordering of variables with in a single access block must be in the order they appear but different blocks can be arranged in arbitrary order. For example:
class Foo
{
public:
int x;
int y;
private:
int _x;
int _y;
};
address of x < address of y
address of _x < address of _y
But you cannot determine relation between address of x and _x. Compiler is free to place then in any order.
-Saurabh
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I don't think so. Can you provide a link to the section that says so?
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Okay I admit I made the comment based on excellent book "Inside the C++ Object Model".
But I check the C++ standard and it is there in Section 9.2 point 12:
"Nonstatic data members of a (non-union) class declared without an intervening access-specifier are allocated so that later members have higher addresses within a class object. The order of allocation of non-static data members separated by an access-specifier is unspecified (11.1). Implementation alignment requirements might cause two adjacent members not to be allocated immediately after each other; so might requirements for space for managing virtual functions (10.3) and virtual base classes (10.1)."
and Section 11.1 point 3:
"The order of allocation of data members with separate access-specifier labels is unspecified (9.2)."
-Saurabh
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Thanks.
So it says it is not always safe to assume the order is preserved.
That is what I remembered, however I didn't know the exceptions were documented as well.
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In the example the OP submitted it is always safe. If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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"always" and "example" indicate an interest in the general answer, covering a broad domain.
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Please don't cheat, his question is actually very well defined.  If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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do you really believe the code shown is the actual code?
that was only the tip of some iceberg; we can only guess what stuff is hiding below the surface.
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Of course I don't believe that's the actual code and I'm pretty sure it hides tons of code behind. Anyway my point is still valid (and you know that  ).
BTW it is friday, have a ![Beer | [beer]](https://www.codeproject.com/script/Forums/Images/beer.gif) or two.If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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I thought I recalled what Luc Pattyn said, but went searching and basically came up with the same thing that Saurabh has presented. There is also a difference between the current C++ standard and the draft of the next standard. The current guarantees order only until the next access-specifier specifier.
The text in the draft for the new standard is:
Nonstatic data members of a (non-union) class with the same access control (clause 11) are allocated so that later members have higher addresses within a class object. The order of allocation of non-static data members with different access control is unspecified (11).
So to extend Saurabh's example:
class Foo<br />
{<br />
public:<br />
int x1;<br />
int y1;<br />
<br />
private:<br />
int x2;<br />
int y2;<br />
<br />
public:<br />
int x3;<br />
int y3;<br />
};
The draft for the new standard (unless its been changed from the one I looked at ) guarantees the order x1 - y1 - x3 - y3, while under the current standard the storage order of x1 and x3 is unspecified.Please do not read this signature.
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I have been trying to interface with a software program which uses a message made up of a 20 word array of unsigned shorts;
unsigned short messageData[20];
I have been trying to use data from a home GPS system which includes Lat and Long and heading.; these have been converted from strings to floats.
e.g.
float lat, long, heading;
My problem is that as I know the scaling factors and least Sig Bit (LSB) for the lat, long and heading in the messageData buffer;
e.g.
For lat and long
LSB = 8.377E-08; Twos complement - 32 bits Max/ Min -180 to +180
For Heading
LSB 0.00549306; Twos complement - 16 bits Max/ Min -180 to +180
Setting the heading:-
unsigned short heading = (unsigned short)(newHeading/0.00549306);
messageData[10] = heading;
Getting the heading:-
bool negative;
unsigned short currentField = messageData[10];
if(currentField & 0x8000)
{
negative = true;
}
else
negative = false;
float heading = (currentField & 0x7FFF) * g_nScalings[wordPos];
if(negative)
heading = -(180 - heading);
But this does not work as I expected; am I missing something?
As for the 32 bit latitude, I was going to this:-
Setting the Latitude:-
union
{
int lat_long;
unsigned short buff[2];
}convert;
unsigned short highWord, lowWord;
int newData = (int)(fEngValue/8.377E-08);
convert.lat_long = newData;
highWord = convert.buff[1];
lowWord = convert.buff[0];
I need to get and set data in the message that is of type unsigned short and use in my program as scaled floats.
Any suggestions please.
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Could you please elaborate a bit. 
Could you post inputs, wrong and expected outputs?
 If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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