C / C++ / MFC

Re: Insert a Container App

27-Dec-22 22:03

And previously answered back in March this year: Re: How to find what name and where the (bluetooth) library is located? - Linux Programming Discussion Boards[^].

Insert a Container App

Glenn Meadows 202227-Dec-22 5:07

Glenn Meadows 2022

27-Dec-22 5:07

First off, I'm not asking for anyone to write code for me. I would like to programmatically drop a Microsoft Project application into my Windows application in a specified location and then be able to drag and drop a file onto the container app? Any hints on how? Thanks

Richard MacCutchan27-Dec-22 22:06

Re: Insert a Container App

27-Dec-22 22:06

Glenn Meadows 2022 wrote:
programmatically drop a Microsoft Project application into my Windows application

What exactly do you mean by that? As to your second question, drag and drop of files is fully supported in Windows; Google will find you plenty of samples.

David Crow28-Dec-22 4:49

David Crow

28-Dec-22 4:49

Glenn Meadows 2022 wrote:
I would like to programmatically drop a Microsoft Project application into my Windows application in a specified location...

This reminds me of what COM was used for decades ago.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles

Having trouble with a function in C

BuilderboiYT26-Dec-22 15:38

BuilderboiYT

26-Dec-22 15:38

<pre lang="C"></pre>In my program, I am asking the user to input a date(in just integers ie 12 31 2019 367) and the number of days they add to it. In one of my functions, this is precisely what I am doing.

The user inputs 12 31 2019 367, and the program is meant to print 1 1 2021, but instead prints 1 1 2020(a year behind)...

What I did(Sorry for a lot of code, I tried to keep it simple and clean):

int days_in_month[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

void add_days_to_date(int *mm, int *dd, int *yy, int days_left_to_add)
{
int days_left_in_month;
while(days_left_in_month > 0)
{
days_left_in_month = days_in_month[*mm] - *dd;
// days_left_in_month = days_in_month[*mm] - *dd;
if (days_in_month[2] && is_leap_year(*yy) == true)
{
days_left_in_month++;
}
} // end while
printf("after while\n");
if(days_left_to_add > days_left_in_month)
{
days_left_to_add -= days_left_in_month;
*dd = 1;
if(*mm == 12)
{
*mm = 1;
(*yy)++;
}
else
{
(*mm)++;
}
}
else
{
*dd += days_left_to_add;
days_left_to_add = 0;
}
}
int main()
{
int mm, dd, yy, days_left_to_add;
printf("Please enter a date between the years 1800 and 10000 in the format mm dd yy and provide the number of days to add to this date:\n");
scanf("%d %d %d %d", &mm, &dd, &yy, &days_left_to_add);
// printf("\nREAD\n");
//These are pointers, so they have to be at certain location i.e. int* mm = &mm
add_days_to_date(&mm, &dd, &yy, days_left_to_add);
printf("%d %d %d\n", mm, dd, yy);
}
What I got after inputs:

Inputs: 12 31 2019 367

Output: 1 1 2020(meant to be 1 1 2021)

Thank you in advance and for your time and patience...</pre>

Victor Nijegorodov26-Dec-22 20:12

Victor Nijegorodov

26-Dec-22 20:12

You have to debug your code to see where, how and why it "calculates" wrong result!

Richard MacCutchan26-Dec-22 22:10

26-Dec-22 22:10

Your code is somewhat confusing, but I did notice the following:

C++

int days_left_in_month; // *** this needs to be initialised to some value
while(days_left_in_month > 0)
{
days_left_in_month = days_in_month[*mm] - *dd;
// days_left_in_month = days_in_month[*mm] - *dd;
if (days_in_month[2] && is_leap_year(*yy) == true) // ***days_in_month[2] is always non-zero, you should be checking if month is greater than 2.
{
days_left_in_month++;
}
} // end while

The actual logic needed is as follows:

Set days_in_year to the actual number of days up to the date given, which in the case above should be 365.
Add days_to_add to days_in_year.
While days_in_year > 365
{
    add 1 to year
    subtract 365 from days_in_year
}
Use the remaining value of days_in_year to calculate the month and day.

Obviously an adjustment for leap years will be needed somewhere in there.

Mircea Neacsu26-Dec-22 22:34

Mircea Neacsu

26-Dec-22 22:34

As Victor was saying, this is the tough part of a programmer's job: finding the errors in your code. Most of the time you are on your own when doing it but in this case I'll try to do part of it with you hoping the experience will be useful.

Before we start, when posting code here, try to paste it between the <pre></pre> tags. It makes it for a much nicer and easier to read code.

int days_in_month[] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

void add_days_to_date (int* mm, int* dd, int* yy, int days_left_to_add)
{
  int days_left_in_month;
  while (days_left_in_month > 0)

Now, ask yourself, what is the value of days_left_in_month when the computer tries to evaluate the while loop for the first time? The answer is that it is not known. This is an "uninitialized local variable" bug and it is very common. The compiler has reserved space for the variable but its content can be anything. We have to fix this.

while (days_left_in_month > 0)
{
  days_left_in_month = days_in_month[*mm] - *dd;
  if (days_in_month[2] && is_leap_year (*yy) == true)

Oops, here is another bug: you wrote days_in_month[2] which is 28 and clearly not zero but what you probably had in mind was more like:

if (month == 2 && is_leap_year(*yy) == true)

If we fix the two errors we found your code will be looking something like this:

void add_days_to_date (int* mm, int* dd, int* yy, int days_left_to_add)
{
  int days_left_in_month;
  days_left_in_month = days_in_month[*mm] - *dd;
  if (*mm == 2 && is_leap_year (*yy))
    days_left_in_month++;

Now it's really the time to start a loop but this loop will have to run until the days_left_to_add is greater than days_left_in_month.

Here I'll stop and let you finish the code. Post back the result and I'll give you more feedback on algorithm and style.

EDIT - I see that while I was writing my long convoluting answer Richard had already made the same points in a more concise form Smile | :)

Mircea

Richard MacCutchan26-Dec-22 23:39

Invalid comparator for STL map

26-Dec-22 23:39

Yes, mine was concise, but your comments still added some good detail.

ForNow25-Dec-22 18:08

25-Dec-22 18:08

Hi

I am getting invalid comparator for the following code and I just dont get it at the very end there is always a path to return

C++

struct usingrange
{
	ESDID esdid;
	int start;
	int end;
	
	usingrange() { start = 0; end = 0; return; }
  bool operator<(const usingrange x) const {
	  if (esdid <= x.esdid)  return esdid <= x.esdid;
	  if (start <= x.start) return start <= x.start; if (end <= x.end) return end <= x.end;
	                                                   else
		                                                 return FALSE;

Daniel Pfeffer25-Dec-22 19:36

Daniel Pfeffer

25-Dec-22 19:36

Shouldn't you be passing usingrange as a reference to your comparison function?

C++

bool operator<(const usingrange& x) const

Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.

ForNow25-Dec-22 21:33

25-Dec-22 21:33

It’s a member of key type

ForNow26-Dec-22 5:14

26-Dec-22 5:14

this is were I am getting the exception at the line with STL_VERIFY

C++

// FUNCTION TEMPLATE _Debug_lt_pred
template <class _Pr, class _Ty1, class _Ty2,
    enable_if_t<is_same_v<_Remove_cvref_t<_Ty1>, _Remove_cvref_t<_Ty2>>, int> = 0>
constexpr bool _Debug_lt_pred(_Pr&& _Pred, _Ty1&& _Left, _Ty2&& _Right) noexcept(
    noexcept(_Pred(_Left, _Right)) && noexcept(_Pred(_Right, _Left))) {
    // test if _Pred(_Left, _Right) and _Pred is strict weak ordering, when the arguments are the cv-same-type
    const auto _Result = static_cast<bool>(_Pred(_Left, _Right));
    if (_Result) {
        _STL_VERIFY(!_Pred(_Right, _Left), "invalid comparator");

this is my code

C++

struct usingrange
{
	ESDID esdid;
	int start;
	int end;
	
	usingrange() { start = 0; end = 0; return; }
  bool operator<(const usingrange& x) const {
	  if (esdid < x.esdid)
		  return esdid < x.esdid;
	  if (start < x.start) 
		  return start < x.start;
	  if (end < x.end) return end < x.end;
	  else
		  return x.end < end;

when I change mt code to

C++

bool operator<(const usingrange& x) const {

    return start < x.start;
 }

everything works I dont get it the operator is excepting a bool retrun code true or false in either I retrun that

Graham Breach26-Dec-22 6:15

Graham Breach

26-Dec-22 6:15

Does your ESDID class have an operator<() function? If not, add one.

ForNow26-Dec-22 6:51

26-Dec-22 6:51

Thank you so much actually everything is a structure I am a very open Smile | :)

person

I got to tell you something you C++ guys a geniuses

ForNow26-Dec-22 7:39

26-Dec-22 7:39

still getting the exception if the key to the map is a structure

consisting of a char[4] and 2 int how would I set < operator

the only way I got it to work

was by return int1 < x.int1

what would like to do

is concatenate all of them in 12 bytes and compare 12 bytes against 12 bytes
thanks

ForNow26-Dec-22 8:31

26-Dec-22 8:31

Since my data was 12 bytes long I was lucky there happened to be a data type 16 bytes long a "long double" I just filled the first 4 bytes with zeros and

C++

;
struct usingrange
{
	ESDID esdid;
	int start;
	int end;
	
	usingrange() { start = 0; end = 0; return; }
  bool operator<(const usingrange& x) const {
	  union
	  {
		  long double a;
		  char str1[16];
	  }c;
	  union
	  {
		  long double b;
		  char str2[16];
	  }d;
	
	  ::memset(&c.str1, 0x00, 16);
	  ::memset(&d.str2, 0x00, 16);
	  ::memcpy(&c.str1[4], &esdid, 4);
	  ::memcpy(&c.str1[8],&start,4);
	  ::memcpy(&c.str1[12], &end, 4);
	  ::memcpy(&d.str2[4], &x.esdid, 4);
	  ::memcpy(&d.str2[8], &x.start, 4);
	  ::memcpy(&d.str2[12], &x.end, 4);

	  return c.a < d.b;

	//	  return usingrange  < x;
	//	  if (start < x.start) 
     //   return start < x.start;
//		  return x.end < end;

 }
 
};

k505426-Dec-22 15:49

k5054

26-Dec-22 15:49

That has a couple of issues. Firstly, you are invoking undefined behavior: Union declaration - cppreference.com
Secondly, you're expecting that the bit patterns of 2 doubles can be compared. This may not be the case, as you may a NaN this way, and then any comparison will return false:

Shell

[k5054@localhost tmp]$ cat example.c 
#include <stdio.h>

int main()
{
    double d = 0.0 / 0.0;  // produces NaN 
    printf("1.0 < d = %d\n", 1.0 < d);
    printf("d < 1.0 = %d\n", d < 1.0);
    printf("d == d  = %d\n", d == d);
}
[k5054@localhost tmp]$ gcc example.c -o example
[k5054@localhost tmp]$ ./example 
1.0 < d = 0
d < 1.0 = 0
d == d  = 0
[k5054@localhost tmp]$

As we can see in the above code, NaN compared to anything, even itself returns false.

If all you want to do is compare bits, you might as well just go ahead and use memcmp()

C++

*#35;include <cstring>
struct usingrange {
    ESDID esdid;
    int start;
    int end;
    // ... other stuff ...
    bool operator<(const usingrange& x)const {
        return ::memcmp(this, &x, sizeof(*this)
    }
};

This relies on the fact that the sizeof a struct or a class is the size of its individual members. This only becomes tricky if your struct/class includes STL or other objects like std::string or std::vector.

Keep Calm and Carry On

ForNow26-Dec-22 21:06

26-Dec-22 21:06

The return using memcmp as operands will get an exception in order to get around this I need to to have to have the syntax return operand1 < operand2 truthfully the order of the items is not that important as long as I am able to retrieve the data by key thanks

Graham Breach26-Dec-22 21:42

Graham Breach

26-Dec-22 21:42

I think you're making it too complicated:

C++

struct ESDID
{
  char c[4];

  bool operator<(const ESDID& other) const
  {
    return c[0] < other.c[0] && c[1] < other.c[1] &&
      c[2] < other.c[2] && c[3] < other.c[3];
  }
}

struct usingrange
{
  ESDID esdid;
  int start;
  int end;

  bool operator<(const usingrange& other) const
  {
    return esdid < other.esdid && start < other.start &&
      end < other.end;
  }
}

I've used && and < because you do not want operator<() to return true for two different objects when you swap them around.

ForNow27-Dec-22 1:22

Read Access exception in xtree for map::insert

27-Dec-22 1:22

just tried it that did it thank you Smile | :)

ForNow24-Dec-22 17:18