Managed C++/CLI

Re: Mixing managed and unmanaged code

7-Jun-02 21:48

Nish - Native CPian wrote:
if it allows you to have a managed line of code inside an unmanaged marked function. I should think not!

It doesn't!

Best regards,
Alexandru Savescu

Nish Nishant7-Jun-02 21:45

7-Jun-02 21:45

Alexpro wrote:
It doesn't!

Well, at least, they granularised at the function level instead of at the class level which would have been horrible.

Nish Smile | :)

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Buy it, read it and admire me Smile | :)

Fatest Way Around

Sidney5-Jun-02 15:33

5-Jun-02 15:33

Hi everyone,

I need advice regardin my problem, here's my problem:

I have a Text File(serves as my database) with 3 colums fixed length, example

Name Address Age
AAA 123 Anywhere 12
BBB .... ...
Joseph 345 Somewhere 15
Rosie 098 Cool DC 20

I need to search this Text File, in the real world this Text File migh contain 1 Million records as soon as we populate our database.

My question is... what is the fastest way to search for a particular string in this text file. Note: I only search for the name, If I find the name... I need to get the enrite line and process it.

I will really appreciate any help that you can give me.

Thanks/Regards
Sidney

Alexandru Savescu5-Jun-02 18:01

5-Jun-02 18:01

I will give you a fast, but memeory consuming solution.
Use a std::map to store the name as keys and you make a struct to store the address. Read the whole file and fill the map. Then, when you search the name you will use std::map::find that will do a binary search.
At the end of the program you iterate through the map and write it to the file.

If you have multiple entries with the same name you may consider multimap. Since you post it to the Manage C++ you may also consider hash_map.

Best regards,
Alexandru Savescu

Sidney5-Jun-02 18:22

5-Jun-02 18:22

Thanks Alexandru! I'll see if I can do this, do you have sample code that used STL Map? if you have would you be so kind to share it with me? And by the way just for info... the fields are of Fixed length, example

Field Name Position Length
Fld1 1 10
Fld2 11 21
etc...

Thanks/Regards
Sidney

Alexandru Savescu5-Jun-02 18:22

5-Jun-02 18:22

You can look at the article on CP about STL here. Also you can read MSDN (the one that comes with .NET is nicer than the VC6.0's one), or the SGI documentation.

Best regards,
Alexandru Savescu

Sidney6-Jun-02 9:06

6-Jun-02 9:06

Hi Alexandru,

I get an error in my code when I try to use the multimap, the error is "Cannot open include file: 'multimap' C++" can you help me?

here's my code:

#include <string>
#include <iostream>
#include <multimap>
using namespace std;

struct ltstr
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) < 0;
}
};

int main()
{
multimap<const char*,="" int,="" ltstr=""> m;

m.insert(pair<const char*="" const,="" int="">("a", 1));
m.insert(pair<const char*="" const,="" int="">("c", 2));
m.insert(pair<const char*="" const,="" int="">("b", 3));
m.insert(pair<const char*="" const,="" int="">("b", 4));
m.insert(pair<const char*="" const,="" int="">("a", 5));
m.insert(pair<const char*="" const,="" int="">("b", 6));

cout << "Number of elements with key a: " << m.count("a") << endl;
cout << "Number of elements with key b: " << m.count("b") << endl;
cout << "Number of elements with key c: " << m.count("c") << endl;

cout << "Elements in m: " << endl;
for (multimap<const char*,="" int,="" ltstr="">::iterator it = m.begin();
it != m.end();
++it)
cout << " [" << (*it).first << ", " << (*it).second << "]" << endl;
}

Thanks/Regards
Sidney

Alexandru Savescu6-Jun-02 9:35

6-Jun-02 9:35

Hello sidney

The < and > tags were stripped by the html parser. Please send the code between <pre> and </pre> so I can see what you include and what include not. However this code sould work

#include <multimap>
using namespace std;
....

Best regards,
Alexandru Savescu

Sidney6-Jun-02 11:04

6-Jun-02 11:04

Here's the code:

#include <string>
#include <iostream>
#include <multimap>
using namespace std;

struct ltstr
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) < 0;
}
};

int main()
{
multimap<const char*, int, ltstr> m;

m.insert(pair<const char* const, int>("a", 1));
m.insert(pair<const char* const, int>("c", 2));
m.insert(pair<const char* const, int>("b", 3));
m.insert(pair<const char* const, int>("b", 4));
m.insert(pair<const char* const, int>("a", 5));
m.insert(pair<const char* const, int>("b", 6));

cout << "Number of elements with key a: " << m.count("a") << endl;
cout << "Number of elements with key b: " << m.count("b") << endl;
cout << "Number of elements with key c: " << m.count("c") << endl;

cout << "Elements in m: " << endl;
for (multimap<const char*, int, ltstr>::iterator it = m.begin();
it != m.end();
++it)
cout << " [" << (*it).first << ", " << (*it).second << "]" << endl;
}

Thanks/Regards
Sidney

Alexandru Savescu6-Jun-02 19:50

6-Jun-02 19:50

Well, the multimap header does not exists. Include <map> and it will work;

#include <map>
using namespace std;
etc.

Best regards,
Alexandru Savescu

Sidney5-Jun-02 18:28

5-Jun-02 18:28

And also, I just want to make it clear... if I have same name in my name field I can use the STD::MAP? if so how can I use the multimap? and is Hash_map fast too? can I also have more info about it?

Thanks/Regards
Sidney

Sidney6-Jun-02 9:03

6-Jun-02 9:03

Hi everyone,

i tried to use the multimap(STL) but I got an error "fatal error: Cannot open include file: 'multimap' C++" I alread installed the all the files that I got from sgi... STL Version 3.3, I installed it in "C:\Program Files\Microsoft Visual Studio\VC98\Include"

What could be the problem?

Thanks/Regards
Sidney

Alexandru Savescu7-Jun-02 10:03

7-Jun-02 10:03

I think you need not replace the STL that comes with Visual C with the SGI implementation.

Best regards,
Alexandru Savescu

WinForms?

Alexandru Savescu3-Jun-02 11:55

3-Jun-02 11:55

Again with some newbie question.

I have started a C# windows application and it look really nice with all those new controls and the WinForms stuff (looks much more to Delphi than VB 6 though Wink | ;)

). I was wondering how I can use WinForms in MC++? I mean draging and dropping WinForms components on the managed form and stuff like that.

Thanks

Best regards,
Alexandru Savescu

James T. Johnson3-Jun-02 12:27

James T. Johnson

3-Jun-02 12:27

You can't

MC++ lacks the CodeDOM support which is required for a visual designer to write the neccesary code.

James

Simplicity Rules!

Rama Krishna Vavilala3-Jun-02 15:42

Rama Krishna Vavilala

3-Jun-02 15:42

Check this out. If you have VB6 you can use the designer. I have not yet tried it.

http://www.gotdotnet.com/userfiles/toml/VBWinForms.zip

Nish Nishant3-Jun-02 19:31

3-Jun-02 19:31

http://www.codeproject.com/useritems/mcppwinforms01.asp

http://www.codeproject.com/managedcpp/mcppwinforms02.asp

http://www.codeproject.com/useritems/mcppoutlookgui.asp

Nish

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Alexandru Savescu4-Jun-02 6:41

4-Jun-02 6:41

Thanks Nish, but as you said in the first article, there is now GUI support in Manage C++ Frown | :(

Best regards,
Alexandru Savescu

Nish Nishant4-Jun-02 17:30

Do I have to use pointers only?

4-Jun-02 17:30

Alexpro wrote:
Thanks Nish, but as you said in the first article, there is now GUI support in Manage C++

Yeah, that's really sad!!!

Nish Frown | :(

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Alexandru Savescu2-Jun-02 21:57

2-Jun-02 21:57

Hi!

I just my first semi-project in .NET that combines both MFC and MC++ and it works fine! However, when I needed to use any .NET classes I had to declare them as pointers and pass pointers to methods etc., like this

SqlConnection* s = new SqlConnection();
f (s);

Is this the only way it works? Confused | :confused:

Apparently yes, and I feel sad, I've been using C++ for a while and got used to using references and not pointers.... Rose | [Rose]

Best regards,
Alexandru Savescu

Nish Nishant3-Jun-02 4:20

3-Jun-02 4:20

You'll have to create all reference types on the heap. Thus you cannot have a String but only a String*.

On the other hand you can have value types on the stack.

Nish

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Alexandru Savescu3-Jun-02 6:27

3-Jun-02 6:27

Thanks Nish, but could you please provide me with some examples with those differences?

Thanks.

Best regards,
Alexandru Savescu

Nish Nishant3-Jun-02 7:57

3-Jun-02 7:57

Alexpro wrote:
Thanks Nish, but could you please provide me with some examples with those differences?

//String has to be on the heap
//It's an __gc class
String *s = new String("hey there");

//Point is a value type
Point p = Point(10,19);

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Alexandru Savescu3-Jun-02 9:24

3-Jun-02 9:24

Thanks! I better lookup in the documentation to see the difference between refernce types and value types! Unsure | :~

Best regards,
Alexandru Savescu

Nish Nishant3-Jun-02 17:59