C / C++ / MFC

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 4:05

Use std::sort to sort the vector. Add an operator < for your struct to define the sort order or code a predicate function or functor and pass it to std::sort.

Steve

all_in_flames27-Mar-07 5:16

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 5:16

Thanks for the article Christian, and the suggestion, Stephen. I will try to follow the instructions in the article. I appreciate the help, and the speedy replies Smile | :)

Does this logic make sense in context?

void SortVecAscending(vector<Wizard> &wizVector, string prop)
{
// Sort vector smallest to largest, according to prop(erty)
bool compare_Wizards(const Wizard& a, const Wizard& b)
{
return a.prop < b.prop;
}

std::sort(wizVector.begin(), wizVector.end(), compare_Wizards);
}

Christian Graus27-Mar-07 6:02

Christian Graus

27-Mar-07 6:02

Yes, that looks like it should work.

Re: Sorting a vector of non-primitive data types (structs)

Stephen Hewitt27-Mar-07 13:33

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 13:33

C++ does not support local functions (functions in functions). You can have functors in function however.

Steve

Stephen Hewitt27-Mar-07 13:33

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 13:33

C++ does not support local functions (functions in functions). You can have functors in function however.

Steve

all_in_flames27-Mar-07 12:12

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 12:12

Thanks again for all your help, gentlemen. I got the sorting working with no more problems.
However, now that I have moved on to the searching portion, I find that the way the project is designed,
I have to search for values in the structs that are NOT strings.

To refresh your memory:
struct Wizard
{
string FirstName;
string LastName;
int Grade;
double WandWeight;
};

Is there any viable way to convert a string to an int, a string to a double, or vice versa?
I have attempted to use static_cast<string>() on the int and double values, and static_cast<int>() / static_cast<double>() on the string values, but the compiler didn't like those conversions.

I have looked around, and there is nothing available to me without downloading someone's class and using it. Since this is a school project, I have a feeling that would be frowned upon.

Any ideas?

If any clarification is needed, simply ask.

Stephen Hewitt27-Mar-07 13:47

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 13:47

There are multiple ways, here's one:

// CommandLine.cpp : Defines the entry point for the console application.
//
 
#include "StdAfx.h"
#include <iostream>
#include <string>
#include <sstream> // For 'istringstream'.
 
int main()
{
	using namespace std;
 
	string s = "1234";
	int num;
	istringstream ss(s);
	ss >> num;
	if (ss)
	{
		cout << "Number is " << num << endl;
	}
 
	return 0;
}

And another:

// CommandLine.cpp : Defines the entry point for the console application.
//
 
#include "StdAfx.h"
#include <iostream>
#include <string>
#include <cstdlib>
 
int main()
{
	using namespace std;
 
	string s = "1234";
	int num = atoi(s.c_str());
	cout << "Number is " << num << endl;
 
	return 0;
}

The second method is easier but error handling is more difficult as if no valid conversion could be performed, a zero value is returned. Also, in the first version simply changing the type of the num variable will make the code work different types but the second version requires a distinct function for each type: atoi only works for ints.

Steve

all_in_flames27-Mar-07 13:54

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 13:54

Thanks again!
I ended up using the stringstream approach, as our prof is fanatical about us not using "pure" C functions.

You guys are life savers!

Regards,

Bryan

Stephen Hewitt27-Mar-07 13:57

Re: Sorting a vector of non-primitive data types (structs)

27-Mar-07 13:57

Your professor is a wise man.

Steve

Michael Dunn27-Mar-07 20:36

Michael Dunn

27-Mar-07 20:36

all_in_flames wrote:
Is there any viable way to convert a string to an int, a string to a double, or vice versa?

For future reference, we have a FAQ here Smile | :)

--
6.3 How can I change a number into its string representation, or vice versa? [^]

--Mike--
Visual C++ MVP Cool | :cool:

LINKS~! Ericahist | PimpFish | CP SearchBar v3.0 | C++ Forum FAQ

Ford, what's this fish doing in my ear?

Re: Sorting a vector of non-primitive data types (structs)

all_in_flames28-Mar-07 2:16

28-Mar-07 2:16

Thanks for the info, Mike!
I'm a codeproject n00b, but I get the newsletter! Wink | ;)

lparam and wparam

Try27-Mar-07 2:59

Try

27-Mar-07 2:59

What are these 'lparam' and 'wparam' ? Where can i get info abt these?

Consider:
BOOL PostMessage(
UINT message,
WPARAM wParam = 0,
LPARAM lParam = 0
);

MSDN says
The content of 'lparam' and 'wparam' parameter depends on the message being posted.
What will be the values when mouse is clicked or key is pressed?

Thanks in Advance.

David Crow27-Mar-07 3:03

David Crow

27-Mar-07 3:03

LameThought wrote:
What are these 'lparam' and 'wparam' ?

They are message-specific values. Some messages use one, the other, both, or neither.

LameThought wrote:
Where can i get info abt these?

MSDN, CP, Google.

LameThought wrote:
What will be the values when mouse is clicked or key is pressed?

Again, it all depends on the specific message you are inquiring about.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Try27-Mar-07 3:12

Try

27-Mar-07 3:12

Now, i want to Set Focus for Edit Box in Dialog using PostMessage, then what will be the values of both?

David Crow27-Mar-07 3:18

David Crow

27-Mar-07 3:18

Use the SetFocus() function for this.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Michael Dunn27-Mar-07 20:40

Michael Dunn

27-Mar-07 20:40

In a dialog, use WM_NEXTDLGCTRL which automagically handles the subtleties in how dialogs handle focus. More from Raymond: Clickety[^]

--Mike--
Visual C++ MVP Cool | :cool:

LINKS~! Ericahist | PimpFish | CP SearchBar v3.0 | C++ Forum FAQ

Ford, what's this fish doing in my ear?

prasad_som27-Mar-07 4:00

prasad_som

27-Mar-07 4:00

You should use SetFocus API in this case as David said earlier.
If you see documentation for WM_SETFOCUS, it will tell you, what should be values passed, as wParam and lParam.
It applies to all windows messages.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Christian Graus27-Mar-07 3:04

Christian Graus

27-Mar-07 3:04

I think you will find WPARAM is a WORD and LPARAM is a long. MSDN is right, they are generic parameters, what they mean changes according to what the message is. MSDN will tell you what they mean in each instance, you just need to find the help for the message you're after.