C / C++ / MFC

Scott H. Settlemier30-Sep-02 10:14

Scott H. Settlemier

30-Sep-02 10:14

int n=S.GetLength(); // this is icky
S.ReleaseBuffer(File.Read(S.GetBuffer(n),n));

ns30-Sep-02 10:21

30-Sep-02 10:21

Oh. So I dont need the LPTCTSR thing for read because GetBuffer returns the pointer to the string? Thanks for the compact coding.

Appreciate your help,
ns

Scott H. Settlemier1-Oct-02 7:36

Scott H. Settlemier

1-Oct-02 7:36

Argh. I can't stand it any longer.
Just leaving with a note that the above
is "icky" wont make the itch go away.
I wrote something knowingly bad above. Blush | :O

This may be pedantic but I gotta get rid of the itch. Smile | :)

GetBuffer returns a pointer to a buffer to which you may
safely store directly into the CString object, but using
a CString whose length happens to match the amount of
data you are reading in is just bad practice.

If one knows the amount of data to be read, then one
should specify it explicitly. e.g.

int n=128; // 128 byte field for planet name<br />
CString Planet;<br />
// read all 128 bytes and set CString to just the 0-terminated portion<br />
Planet.ReleaseBuffer(File.Read(Planet.GetBuffer(n),n)!=n?0:-1);

Better yet, create structures that mirror the fixed length
portions of the file and read them in entirety. e.g.

struct Names<br />
{<br />
   enum {NAMESIZE=128};<br />
   char  Planet[NAMESIZE];<br />
   char  System[NAMESIZE];<br />
   // etc.<br />
};<br />
<br />
ABC MyNames;<br />
VERIFY(File.Read(&MyNames,sizeof(MyNames))==sizeof(MyNames));

and if you need it in a CString later:

MyNames.Planet[NAMESIZE-1]=0; // make sure 0-terminated<br />
CString S=MyNames.Planet;

ns1-Oct-02 7:40

1-Oct-02 7:40

Thanks! That gives me a lot to think about... Smile | :)

Appreciate your help,
ns

a map question

ns30-Sep-02 8:57

30-Sep-02 8:57

I have a map object:

std::map [long , CString] m_MapForMerge;

(forgot how to replace angled brackets for definition of map for CP)

Its just declared but not created yet.

I get the values of the its two components in a loop, nSize and tempBufString . I want to fill the map with these two values. Is this the way to do it?

tempBuffer = new char[nSize];

    ReadPFile(sPathName, tempBuffer);

    tempBufString = tempBuffer;

    m_MapForMerge[nSize] = tempBufString;

or should it be:

tempBufString = m_MapForMerge[nSize];

Appreciate your help,
ns

Anonymous30-Sep-02 9:20

Anonymous

30-Sep-02 9:20

The first way is the correct one.

RedZenBird30-Sep-02 12:16

RedZenBird

30-Sep-02 12:16

careful with map inserts....duplicate keys will bounce off of a map [if someone knows how to 'turn this off' please clue me in ]....maybe you know that however.....very careful map users will use a 'find' call first to make sure the map 'slot' is available....if 'find' comes back != end() then something is already at that location in the map and you may have to do some extra logic to deal with that case...

Just trying to keep the forces of entropy at bay

jhwurmbach30-Sep-02 21:49

jhwurmbach

30-Sep-02 21:49

RedZenBird wrote:
duplicate keys will bounce off of a map [if someone knows how to 'turn this off' please clue me in ]

Do you mean 'std::multimap'?
It can hold the same key more than once, but finding an entry gets slightly more complicated, as you cant possibly know how many entrys gou get.

Re: Create array of CArray

ns1-Oct-02 2:26

1-Oct-02 2:26

Never used them, but multimaps accept duplicate keys I believe...

Thanks so much for the responses. I finally had to use a vector with a two element structure type precisely because of bouncing off of duplicate keys.

Appreciate your help,
ns

Create array of CArray

ooosawaddee330-Sep-02 7:29

ooosawaddee3

30-Sep-02 7:29

I want to create array of CArray.

If I have this below CArray

CArray<unsigned char,="" unsigned="" char=""> m_data;

I want to create Array of m_data. Do you know how to do that ?

jmkhael30-Sep-02 7:30

Cfile and consecutive writes

30-Sep-02 7:30

CArray m_array [ 5 ] ;

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

ns30-Sep-02 7:18

30-Sep-02 7:18

I'm working toward checking this out myself, but am curious. If I write a buffer to a CFile object, then Write buffer#2, followed by buffer#3, all before closing the file, one after another, the output file wil have the three buffers concatenated. Is that correct? I'll have three binary buffers so I dont know if I can tell if they are in order etc....want to be sure. They dont start afresh at the beginning of the CFile at each Write, right?

Thanks,
ns

Re: Cfile and consecutive writes

jmkhael30-Sep-02 7:21

Re: Cfile and consecutive writes

30-Sep-02 7:21

no they dont start at the begining each time, they get concatenated Smile | :)

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

ns30-Sep-02 7:28

30-Sep-02 7:28

Thanks again! Its great to have you around!

Appeciate it,
ns

Re: Cfile and consecutive writes

jmkhael30-Sep-02 7:33

30-Sep-02 7:33

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

Can anyone help...

Kash30-Sep-02 7:06

Kash

30-Sep-02 7:06

I am trying to draw an xy scatter graph using MSchart (ActiveX) but there is only documentation for VB. I want to draw a y=x^2 graph. This is what I have but returns an error saying "Index is out of bounds".

m_chart.GetPlot().GetAxis(VtChAxisIdX, v).GetAxisTitle().SetText("x");
m_chart.SetTitleText("Simple graph");
m_chart.SetColumnCount(4);
m_chart.SetRowCount(10);
int x,y;
for(y=0;y<4;y++){
m_chart.SetColumn(y);
for(x=0;x<10;x++){
m_chart.SetRow(x);
int a = x*y;
m_chart.SetColumn(a);
}
}
A small example would be helpful

Any ideas?

gije30-Sep-02 7:30

gije

30-Sep-02 7:30

Try setting the index to 1 instead of 0:

for(y=1;y<=4;y++){ ...
for(x=1;x<=10;x++){ ...

Kash30-Sep-02 7:29

Kash

30-Sep-02 7:29

I get the same error, I think it has something to do with m_chart.SetColumn().
I have a feeling this may not be the right Function but don't know what I'd put in it's place.

jmkhael30-Sep-02 7:54

30-Sep-02 7:54

http://softwaredev.earthweb.com/msnet/vc/article/0,,12081_629511,00.html Sorry outside CP Smile | :)

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;