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Try this instead:
SYSTEMTIME varTime;
GetSystemTime(&varTime);
varTime.wMonth--;
After the third statement, the month would be decremented by one. Kinda obvious, but you asked for it.
Add: Oops! I haven't taken account of the year January. But I think that you must be able to do it yourself now. 
Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche
.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]
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What about if you are on 30th or 31st of march? Or any other 31st where the moth before only 30 has? Won't it crash? :P
EDIT: Question was already below, I should read all before posting 
Regards.
--------
M.D.V. 
If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
“The First Rule of Program Optimization: Don't do it. The Second Rule of Program Optimization (for experts only!): Don't do it yet.” - Michael A. Jackson
Rating helpfull answers is nice, but saying thanks can be even nicer.
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That was discussed two posts below here[^]. But that is an exercise that the OP must take care of. 
Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche
.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]
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Nelek wrote: What about if you are on 30th or 31st of march? Or any other 31st where the moth before only 30 has? Won't it crash?
BTW, I forgot to mention it won't *Crash* anyways.
SYSTEMTIME is just a structure and it can store the value you put into it. The trouble may come, only when a call to something like SetTime() is called with the new time structure after decrement has happened.
Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche
.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]
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I think the below code will do the trick, anyway verifying it is up to you 
CTime today = CTime::GetCurrentTime();
CTime aMonthAgo;
CTimeSpan ts(today.GetDay(),0,0,0);
aMonthAgo = today - ts;
aMonthAgo += CTimeSpan( - aMonthAgo.GetDay() + today.GetDay(), 0, 0, 0);
[added #1]
That was buggy, forget it  . Anyway are you aware that your requirement cannot be satisfied when current day is for instance March 31th?
[/added #1]
[added #2]
Fixed code:
CTime today = CTime::GetCurrentTime();
CTime aMonthAgo;
CTimeSpan ts( today.GetDay(), 0, 0, 0 );
aMonthAgo = today - ts;
int iSpan = aMonthAgo.GetDay() - today.GetDay();
if (iSpan > 0)
aMonthAgo -= CTimeSpan( iSpan, 0, 0, 0);
This code sets aMonthAgo to:
(1) a date having the same day (of month) of current date, but month equal to previous month, whenever such requirement can be satisfied.
(2) Last day of previous month whenever the requirement (1) cannot be satisfied (for instance when input date is March 31th).
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]
modified on Tuesday, October 14, 2008 6:48 AM
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SYSTEMTIME today, lastMonth;
GetLocalTime(&today);
memcpy(&lastMonth, &today, sizeof(SYSTEMTIME));
if (lastMonth.wMonth > 1)
lastMonth.wMonth--;
else
{
lastMonth.wMonth = 12;
lastMonth.wYear--;
}
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enhzflep wrote: // as long as it's not january,
My 5 for your attention to detail. I missed out on the case where the month could be January!
Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche
.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]
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Oh gee Raj, thanks.![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
Quick question - do I lose thhose points for forgetting to consider the question:
What is the date 1 month prior to the 30th of march?
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That's a flaw of OP's requirements.
The same applies to March 31th (and, for most years, 29th), May 31th,...
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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As CPallini said.
Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche
.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]
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If the current date happens to be March 31st and the year is not a leap year, the most days you'd be off is 3. That said, once you subtract 1 from the current month (use the % operator so that it will wrap back around to December as needed), you may also need to subtract up to 3 days to have a valid date.
"Love people and use things, not love things and use people." - Unknown
"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch
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Hi guy,
does someone know some tricks to increase the time performance
of a VC++ application that need to write a large amount of data
into an Excel Sheet ?
Thanks
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Yup!
Use a multidimensional safearray.
Once upon a time I was filling an Excel sheet with ~10Mb and it took about 40 minutes addressing one cell at a time. With a multidimensional safearray it took ~10 seconds.
"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown
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Thanks a lot !
I try immediately
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That's a nice suggestion.
Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche
.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]
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Rajesh R Subramanian wrote: That's a nice suggestion.
Well, actually it's all the out-of-process calls that are the culprits here. They are ~2000 times slower than ordinary function calls in comparison. Knowing that, it's no rocket science figuring out that making less calls of this type will improve performance. 
"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown
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Overclocking?
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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Hi All, Good Morning.
I am facing compilation errors but I have declared everything properly. Something is missing Please help me. I declared a declared class having 3-4 member functions n variable in header file and defined its functions in source file. Everything was working fine. But Now if I add some #define statements in header file and use those in source file , It is giving error undeclared variable. also if I put the mouse on #define statement it showing the variable with _CURSOR_ appended with.
eg.
#define TRADE_TAG "trd"
if I put the mouse on TRADE_TAG then it will show like TRADE_TAG_CURSOR_ "trd".. dont know why.. also if I right click on TRADE_TAG n then look for declaration then msg box appears variable TRADE_TAG not declared ... can u guide me here.
Second issue.
If I add a member variable or member function to the class declaration n then define in source file , it again gives compilation errors. dont identify class member variables n function. strange thing is that in one function it is recongnising member variables n in the another it is not.. both functions are member of the class. putting mouse on member function defination shows it as member. but on compilation it is giving error then function is not a member of class see the declartion.I m pasting code here. Please help
Header file Kccdatabase.h
#ifndef __KCCDATABASE_INCLUDE__
#define __KCCDATABASE_INCLUDE__
#pragma once
#include "afxdb.h"
class CKccDatabase : public CDatabase
{
private:
char sTradeXML[500];
char sTradeKcc[150];
public:
CKccDatabase();
virtual ~CKccDatabase();
BOOL ConnectKccDatabase(CKccDatabase &;
void InsertTrade(CKccDatabase *);
void ConvertTrdToXML(long RowIndx , bool IsRegularTrade = 1);
void ConvertTrdToKccFormat(long RowIndx , bool IsRegularTrade = 1);
};
source file
#include "KccDatabase.h"
void CKccDatabase::ConvertTrdToXML(long RowIndx , bool IsRegularTrade)
{
sTradeXML="Hello";
}
void CKccDatabase::ConvertTrdToKccFormat(long RowIndx, bool IsRegularTrade)
{
sTradeXML = "Hello";
sTradeKcc= " yes";
}
when I compile this source file cntl+f7 then it gives these errors in
KccDatabase.cpp(126) : error C2039: 'ConvertTrdToKccFormat' : is not a member of 'CKccDatabase'
1> f:\kats_clients_local\kats32\kats32\KccDatabase.h(4) : see declaration of 'CKccDatabase'
1>.\KccDatabase.cpp(151) : error C2065: 'sTradeKcc' : undeclared identifier
1>.\KccDatabase.cpp(152) : error C2065: 'sTradeXML' : undeclared identifier
please note that it is recongnising variable xTradeXML in upper ConvertTrdToXML but not in ConvertTrdToKccFormat ... also when I put cursor on the ConverTrdToKccFormat function defination then It shows this as member of CKccDatabase class ..
the only difference is that i have defind ConvertTrdToXML 4-5 days ago .. and otherone today.. :-9
Can anybody help
thx
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I cannot spot any error in your code. Did you copy pasted this code or typed it yourself in the browser?
-Saurabh
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param_joshi wrote: ...strange thing is that in one function it is recongnising member variables...
Not necessarily. When the compiler sees that a duplicate error would be generated, it will supress the extra ones. For example:
class David
{
int name;
void foo1()
{
naame = 12;
}
void foo2()
{
naame = 13;
}
};This will only generate one compiler error. Once I fix foo1(), only then will the compiler start complaining about foo2().
That aside, I see 2-3 syntax errors with your code snippet. The first is ConnectKccDatabase() is missing a closing parenthesis. The second is that you cannot assign sTradeXML and sTradeKcc to string literals like that. Either make them pointers, or use strcpy(). Since you are using MFC, I'd opt for CString variables instead.
"Love people and use things, not love things and use people." - Unknown
"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch
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Another suggestion: You're using MS Visual Studio right? Try saving cleaning the solution, save everything, close the program, then re-open. Sometimes Visual Studio failes to update intermediate files correctly. Cleaning the solution should delete those. The Re-start the program step is an unfortunate occurance, but I've known it to fix problems. Not sure why, but particularly those having to do with recent changes made in the software not being recognized. Just a thought.
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Hi
Please help me to find out the problem in GetPrinter function.
First I am trying to get the printer handle for the specified printer using OpenPrinter function. .
HANDLE hPrinter = 0;
OpenPrinter ((LPTSTR)(LPCTSTR)strPrinterAddress, &hPrinter, NULL);
This function gets succeed. Using this printer handle I am trying to access the specified printer information’s using the GetPrinter function.
GetPrinter(hPrinter, 2, NULL, 0, &dwNeeded);
if(!dwNeeded)
{
DWORD dwError = ::GetLastError();
ClosePrinter( hPrinter );
}
Even using GetLastError() function I am not able retrieve error message. This function is not failing all the times. When I am trying to print out of 10 times, 6 times the printing is succeed. Only 4 times it’s getting failed. Please help me shoot out this problem.
Thanks
Gokul
modified on Tuesday, October 14, 2008 4:08 AM
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Why do you check dwNeeded instead of GetPrinter return value?
What is GetLastError return value when GetPrinter fails?
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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The Get Printer function will return required buffer size in dwNeeded. I hope this should always be greater than zero. So I checked with the buffer size.
When I am trying to print the last error code it is printed nothing (empty).
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I would check the GetPrinter return value, and call GetLastError only when it fails.
Are you aware that (MSDN [^]):
Remarks
Security Alert The pDevMode member in the PRINTER_INFO_2, PRINTER_INFO_8, and PRINTER_INFO_9 structures can be NULL.
When this happens, the printer is unusable until the driver is reinstalled successfully.
?
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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