Re: MFC dialog based application - C / C++ / MFC Discussion Boards

How to search large database without SQL or alike. Just asking.

Vaclav_13-Jul-15 7:44

13-Jul-15 7:44

I am building a small database app on SAM3x8e hardware and decided that C++ will do.
I basically need to find a matching record and have an idea how to do it.
I don't see any timing issues.

I was just curious how the "big boys" do search on VERY large database.
I have heard about hash tables etc.

OK, I can Goggle , but some pointers would be appreciated.
Cheers
Vaclav

Re: How to search large database without SQL or alike. Just asking.

PIEBALDconsult13-Jul-15 8:10

PIEBALDconsult

13-Jul-15 8:10

I'm unclear on what you are asking. Are you using an existing database product? Or are you trying to create your own database system?

Re: How to search large database without SQL or alike. Just asking.

Richard MacCutchan13-Jul-15 22:11

Richard MacCutchan

13-Jul-15 22:11

It is almost impossible to search a database without an SQL like query language, unless you know the exact structure of the data held inside it.

Re: How to search large database without SQL or alike. Just asking.

jschell15-Jul-15 10:36

jschell

15-Jul-15 10:36

Vaclav_Sal wrote:
I am building a small database app on SAM3x8e hardware...I was just curious how the "big boys" do search on VERY large database.

First part of that is basically incompatible with the second.

In general the solution for your problem is similar in a very broad way in that one must:
1. Understand the data
2. Understand the searches needed.

The solution(s) are then based on that.

So for example it is pointless to use a hash if you are doing regular expression searches on free form text.

Assembly in C Emu8086 branch table

a random user11-Jul-15 2:46

a random user

11-Jul-15 2:46

Hello there, Im trying to make an assembly program that translates a simple switch case program in c without using and commands related to jg or jt only jmp

I tried making something like this:

org 100h

mov si,3

jmp word ptr [jmptab+si]

case1:
PRINTN "Number One"
jmp endcases

case2:
PRINTN "Number Two"
jmp endcases

case3:
PRINTN "Number Three"
jmp endcases

case4:
PRINTN "Number Four"

endcases:

jmptab:
DW case1
DW case2
DW case3
DW case4

mov ah, 0
int 16h
ret

include magshimim.inc

Where did I go wrong?

modified 11-Jul-15 8:53am.

Re: Assembly in C Emu8086 branch table

Daniel Pfeffer11-Jul-15 9:12

Daniel Pfeffer

11-Jul-15 9:12

[This should really go in QA]

Hint:
a. What is the size of each entry in your jump table?
b. How are you indexing the jump table?

If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.

--Winston Churchill

MFC dialog based application

Member 1182280710-Jul-15 2:37

Member 11822807

10-Jul-15 2:37

Completely new to C++ and have been given a task that includes creating an application that uses CString data from a completely separate .h file.
The CStrings consist of info that I need to be able to copy to the clipboard, then be able to paste that text into word etc. I have set up a button in the application so when that button is pressed it executes what I want it to do (read the CString data and copy it to the clipboard).
For a person of my skill level this is difficult and my colleagues do not have the time to support me on this learning project so I thought I could get some advice and pointers here. Any help would be greatly appreciated. I am an apprentice working in software for 2 months.

Kind regards,
Luke

Re: MFC dialog based application

David Crow10-Jul-15 2:59

David Crow

10-Jul-15 2:59

Member 11822807 wrote:
I have set up a button in the application so when that button is pressed it executes what I want it to do (read the CString data and copy it to the clipboard).

This is what it does or this is what you want it to do?

Member 11822807 wrote:
...so I thought I could get some advice and pointers here. Any help would be greatly appreciated.

So what EXACTLY do you have a question about?

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

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Re: MFC dialog based application

Richard MacCutchan10-Jul-15 4:15

Richard MacCutchan

10-Jul-15 4:15

You have not actually told us what help you want, so I am guessing you want to know how to:

read from a text file: https://msdn.microsoft.com/en-us/library/a499td6y.aspx[^].
use the clipboard: https://msdn.microsoft.com/en-us/library/80db3kax.aspx[^].
paste data to Word. This requires knowledge of COM and the Word interfae. A far more advanced topic.

How do I add Thread in Dll

AmbiguousName9-Jul-15 22:12

AmbiguousName

9-Jul-15 22:12

Hello guys. I am trying to make a simple TSP using Julmar TSP SDK. I am able to make a skeleton TSP which gets detected by Windows and its added line can be seen from Phone.exe.

I want to add a thread in this TSP, which generates fake call to Phone.exe

How do I take it further? Should I add a main()and instantiating all the classes in it, in my .tsp project? Or will I be doing something in TSPUI project (so that I setup few things during manual installation of TSP)? Thanks for giving any pointer.

This world is going to explode due to international politics, SOON.

Estimate time of execution c-function execution

CodingStyle7-Jul-15 5:08

CodingStyle

7-Jul-15 5:08

Hello all!
I need help. I need to estimate function execution time in under Linux OS. I guess that it's right way to estimate code/algorithm performance.

I'm trying, something like this:

#include <time.h>
#include <sys/time.h>
#include <stdio.h>
void test(){
	int i;int s=0;

	for(i=1; i<1000000; i++){s+=sin(i)/i;}
}
float timedifference_msec(struct timeval t0, struct timeval t1)
{
    return (t1.tv_sec - t0.tv_sec) * 1000.0f + (t1.tv_usec - t0.tv_usec) / 1000.0f;
}

int main(void)
{
	struct timeval t0;
	struct timeval t1;
	float elapsed;
	gettimeofday(&t0, 0);
	f1();
	gettimeofday(&t1, 0);
	elapsed = timedifference_msec(t0, t1);
	printf("Code executed in %f milliseconds.\n", elapsed);
	return 0;
}

. But It's wall clock, I'm not sure that I can estimate performance by this way, besides, I need approach which will allow to measure time of each function which I choose. I've heard that there is approach to use CPU-time.

Re: Estimate time of execution c-function execution

Richard MacCutchan7-Jul-15 6:31

Richard MacCutchan

7-Jul-15 6:31

CodingStyle wrote:
I've heard that there is approach to use CPU-time.

And there is even a man page[^] for it.

Re: Estimate time of execution c-function execution

Jochen Arndt7-Jul-15 6:35

Jochen Arndt

7-Jul-15 6:35

For high accuray difference time measurements with Linux use clock_gettime[^] with timer ID CLOCK_MONOTONIC or CLOCK_PROCESS_CPUTIME_ID. This requires including time.h and linking with the real time library librt (link option -lrt).

An example can be found at http://www.guyrutenberg.com/2007/09/22/profiling-code-using-clock_gettime/[^].

Re: Estimate time of execution c-function execution

Dr. Fry7-Jul-15 10:04

Dr. Fry

7-Jul-15 10:04

Yeah. There is such approach like, count the number of ticks to estimate performance. I do not think that it's panacea.
Richard MacCutchan and Jochen Arndt also correct.
But I guess that you mean universal and independent implementation version. Look here.

Re: Estimate time of execution c-function execution

CodingStyle8-Jul-15 0:02

CodingStyle

8-Jul-15 0:02

Thank you!

Re: Estimate time of execution c-function execution

Arthur V. Ratz13-Aug-15 19:29

Arthur V. Ratz

13-Aug-15 19:29

This is probably what you need:

C++

#include <time.h>
#include <sys/time.h>
#include <stdio.h>
void test(){
    int i;int s=0;

    for(i=1; i<1000000; i++){s+=sin(i)/i;}
}

int main(void)
{
    clock_t time[2], timediff;
    float elapsed;
    time[0] = clock();
    f1();
    time[1] = clock();
    elapsed = ((float)abs(time[0] - time[1]))/CLOCKS_PER_SEC;
    printf("Code executed in %f milliseconds.\n", elapsed);
    return 0;
}

preprocessor #include

Vaclav_6-Jul-15 3:12

Vaclav_

6-Jul-15 3:12

I am an innocent bystander of a discussion about how #include directive is handled in IDE.
The IDE in question uses proprietary file "main" name extension (still a text file) and processes #include <header.h> and #include "local_header.h" in that file just fine.

However, when the local_header.h file has <b>another #include <header_1.h></b> in it the compiler "does not see that". That is basically what people who "knows / developed" the IDE are saying.

Including another local file in first local file such as #include "local_header_1.h" is "seen / processed " by IDE.

I was under the impression that #include <file.h > tells the OS to find the file "anywhere" and #include "file.h" tells the OS to search only current / parent directory.

So why is IDE (gcc) getting into the act?

Re: preprocessor #include

C^hris L^osinger6-Jul-15 3:30

C^hris L^osinger

6-Jul-15 3:30

C++

#include <file>

This variant is used for system header files. It searches for a file named file in a standard list of system directories.

C++

#include "file"

This variant is used for header files of your own program. It searches for a file named file first in the directory containing the current file, then in the quote directories and then the same directories used for <file>.

https://gcc.gnu.org/onlinedocs/cpp/Include-Syntax.html[^]

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Re: preprocessor #include

Albert Holguin7-Jul-15 13:29

Albert Holguin

7-Jul-15 13:29

FTFY

Chris Losinger wrote:
This variant is used for system or library header files.

Re: preprocessor #include

Jochen Arndt6-Jul-15 4:41

Jochen Arndt

6-Jul-15 4:41

Vaclav_Sal wrote:
However, when the local_header.h file has <b>another #include <header_1.h></b> in it the compiler "does not see that".

That is wrong. The compiler (or more precise: the preprocessor part) will process such includes.

However, an IDE may do other things with your files before they are passed to the compiler. But GCC is the Gnu Compiler Collection (a collection of command line tools) and not an IDE.

Re: preprocessor #include

PIEBALDconsult6-Jul-15 4:43

PIEBALDconsult

6-Jul-15 4:43

A compiler is not an IDE. An IDE is a front-end to a compiler and it should follow the same rules as the compiler (and pre-processor in this case). If the IDE does not, then it is broken and must be fixed.

Re: preprocessor #include

Vaclav_10-Jul-15 4:07

Vaclav_

10-Jul-15 4:07

Thanks for confirming my suspicions.

Obviously I got the compiler mixed up , so here is the way I view the whole mess.

To get from idea to running code I see these basic blocks

Operating system - with environment configuration
Development application (IDE )
Development tools
Text editor
Main file .*ino
"System " includes - example <stdio.h>
IDE "libraries" - example <LiquidCrystal.h>
Local includes - example "MyClass.h"
Compiler / linker (preprocessor)
Executable code

I think I need to take a look how the compiler handles / finds the path to each include.

I can see if local includes are in SAME directory as the x.ino file it works fine.
But the "system" or "library" includes path are different and that why if fails.

But I want to write code and not troubleshoot the IDE.
Maybe I should use a different IDE.

Cheers
Vaclav

Re: preprocessor #include

Richard MacCutchan10-Jul-15 4:22

Richard MacCutchan

10-Jul-15 4:22

Vaclav_Sal wrote:
But I want to write code and not troubleshoot the IDE.

There is nothing to troubleshoot. Whether you use the IDE or not, the issues are the same. The compiler needs to know the paths of any directories which contain header files that you wish to include in your compilations. The linker needs to know the paths of any directories which contain libraries that are referenced by your project. When you install Visual Studio it sets a default set of both, which gives the paths to all the default library components. If you create a project that uses other headers and libraries then you need to add those paths, and the library names, using the Project Properties link in Solution Explorer. If you want to do it without using the IDE then it is much more hard work and you would probably need to set up some complex batch files, or learn how to use Make: something that is not for the fainthearted.

Re: preprocessor #include

Vaclav_13-Jul-15 7:50

Vaclav_

13-Jul-15 7:50

Richard, I feel you missed my question.
Just FYI, the IDE I am using is pretty tight lipped about "an additional path" I experienced using my VC++. It just was not build to expand...

I posted my question here for reasons which I do not wish to discuss.

Thanks anyway.

Re: preprocessor #include

Richard MacCutchan13-Jul-15 22:05

Richard MacCutchan

13-Jul-15 22:05

Vaclav_Sal wrote:
I feel you missed my question.

No, I think it was clear enough.

Vaclav_Sal wrote:
I posted my question here for reasons which I do not wish to discuss.

Then maybe you should not have posted it.

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