C / C++ / MFC

How to link C code to which Bluetooth library ? ( Linux)

31-Dec-22 5:11

The question is impossible to answer since we have no idea how the access control software works. You need to contact the manufacturers of the door for help.

Member 1496877127-Dec-22 9:31

Member 14968771

27-Dec-22 9:31

I am trying to port this C code into C++.
I am stuck linking to library - few reasons
which library am I supposed to use - libbluetooth or bluetooth ?
I am using QTCreator ( pseudo IDE) and really do not know how the access
the compiler / linker directly , hence not sure if I need to add "-l" but
I can figure that out when I manage to
actually find either library file - so far no luck ( and did ask elsewhere for help with that )

This very old basic C code and there is no way to ask the author.

I just need some assistance to link this code to correct library.

Thanks,
any help with the library issue will be greatly appreciated .

C++

<pre>To compile our program, invoke gcc and link against libbluetooth
# gcc -o simplescan simplescan.c -lbluetooth



Example 4-1. simplescan.c



#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>

int main(int argc, char **argv)
{
    inquiry_info *ii = NULL;
    int max_rsp, num_rsp;
    int dev_id, sock, len, flags;
    int i;
    char addr[19] = { 0 };
    char name[248] = { 0 };

    dev_id = hci_get_route(NULL);
    sock = hci_open_dev( dev_id );
    if (dev_id < 0 || sock < 0) {
        perror("opening socket");
        exit(1);
    }

    len  = 8;
    max_rsp = 255;
    flags = IREQ_CACHE_FLUSH;
    ii = (inquiry_info*)malloc(max_rsp * sizeof(inquiry_info));

    num_rsp = hci_inquiry(dev_id, len, max_rsp, NULL, &ii, flags);
    if( num_rsp < 0 ) perror("hci_inquiry");

    for (i = 0; i < num_rsp; i++) {
        ba2str(&(ii+i)->bdaddr, addr);
        memset(name, 0, sizeof(name));
        if (hci_read_remote_name(sock, &(ii+i)->bdaddr, sizeof(name),
            name, 0) < 0)
        strcpy(name, "[unknown]");
        printf("%s  %s\n", addr, name);
    }

    free( ii );
    close( sock );
    return 0;
}

Re: How to link C code to which Bluetooth library ? ( Linux)

k505427-Dec-22 10:30

k5054

27-Dec-22 10:30

asked and answered in QA, I think.

Keep Calm and Carry On

Re: How to link C code to which Bluetooth library ? ( Linux)

Richard MacCutchan27-Dec-22 22:03

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