C / C++ / MFC

12-Jul-06 5:02

First, I thank those who provided their feedback from earlier post.
I need some tweaking once again

As stated earlier, I have a program that should accept only keyboard input of integers from 1 to 12.

Someone suggested I try the scanf() function. I did something with it as shown below. Currently, it allows all integers as valid input and no other characters (letters, punctuatation, symbols, ect . . .).

This is fine. But, how can I further restrict user input with the scanf() function to allow only integers 1 thru 12? Or should I use another method? This is my first time using scanf. I've already tried the while conditions

while (data >=0 || data <= 13), (data >=0 && data <= 13)

with not much luck. At this point I'm not sure if I should change how I'm retrieving the data (thru cin or getline). This is a very pivotable part of the program and the whole program is dependent on this functionality. Help is appreciated. Smile | :)

char buff[1024];
	unsigned int value;
	int charsRead;

	bool validEntry = false;
	while (!validEntry)
	{ 
	    cout << "Please enter the number of subunits: ";
		cin.getline(buff, 1023, '\n');


        if (sscanf(buff, "%u%n",&value,&charsRead)==1)			
        validEntry = true;
	}

-- modified at 11:13 Wednesday 12th July, 2006

David Crow12-Jul-06 5:17

12-Jul-06 5:17

Does this not work:

do
{
    cout << "Please ... ";
    cin >> value;
} while (value < 1 || value > 12);

It's certainly a lot simpler than all of that other stuff (e.g., validentry, sscanf()).

"The largest fire starts but with the smallest spark." - David Crow

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

Harold_Wishes12-Jul-06 5:39

12-Jul-06 5:39

I ended up doing this instead:

char buff[1024];
  unsigned int value;
  int charsRead;

  bool validEntry = false;
  while (!validEntry)
  {
      cout << "Please enter the number of subunits: ";
      cin.getline(buff, 1023, '\n');


         if (sscanf(buff, "%u%n",&value,&charsRead)==1)
         validEntry = true;

     if (validEntry == true)
             if (value >= 1 && value <= 12)
          break;
         else
          validEntry =false;
  }

It seems to work in main() but I still need to test it in the function I created since that is where I want it. I've had some issues when passing data between functions.

Thanks Smile | :)

-- modified at 11:40 Wednesday 12th July, 2006

David Crow12-Jul-06 5:53

12-Jul-06 5:53

Harold_Wishes wrote:
I ended up doing this instead:

And this is acceptable? It sure seems like a bunch of unnecessary code.

"The largest fire starts but with the smallest spark." - David Crow

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

Harold_Wishes12-Jul-06 6:12

12-Jul-06 6:12

Since I've had so many runtime errors with my output, I decided to leave it as is. I've spent too much time on it already. For me, the scanf() seems to work the best although I'm not very familiar with it. If there is a better solution ( as I'm not an experienced programmer) I would appreciate the feedback.

Thanks Smile | :)

-- modified at 12:28 Wednesday 12th July, 2006

I might mention that the code below does not test for non-numeric values which causes my screen output to scroll endlessly with text. I need the input to be an integer because I'm using it as a counter in the rest of my program.

do{    
	cout << "Please ... ";    
	cin >> data2;


} while (data2 < 1 || data2 > 12);

-- modified at 12:31 Wednesday 12th July, 2006

David Crow12-Jul-06 6:33

12-Jul-06 6:33

Harold_Wishes wrote:
I might mention that the code below does not test for non-numeric values...

True. If that is a requirement, then I would use getchar() instead.

"The largest fire starts but with the smallest spark." - David Crow

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

Zac Howland12-Jul-06 10:12

Zac Howland

12-Jul-06 10:12

You are doing far too much work for this.

// assume min and max are included in range
int getInput(int range_min, int range_max)
{
        int ret = range_min - 1;        // initialized to a invalid entry
        do
        {
                char buffer[100] = {0};
                cout << "Enter a value:  ";
                cin.getline(buffer, 99, '\n');
                ret = atoi(buffer);
                if (range_min > ret || ret > range_max)
                {
                        cout << "Invalid entry!" << endl;
                }
        } while (range_min > ret || ret > range_max);

        return ret;
}

int main()
{
	int count = getInput(1, 11);
	cout << "You entered:  " << count << endl;
}

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week

Zac

earl12-Jul-06 8:52

earl

12-Jul-06 8:52

Harold, what I would do is:

<br />
char buff[1024];<br />
unsigned int value;<br />
int charsRead;<br />
<br />
bool validEntry = false;<br />
while (!validEntry){ <br />
   cout << "Please enter the number of subunits: ";<br />
   cin.getline(buff, 1023, '\n');<br />
   <br />
   if (sscanf(buff, "%u%n",&value,&charsRead)==1 && value >=1 && value <= 12)<br />
      validEntry = true;<br />
}<br />

Otherwise, if you want to use c++ style stuff (I rarely do because I mostly work with windows programs and text strings), you could do sth like this:

<br />
	int test;<br />
	std::string dump;<br />
<br />
	bool valid = false;<br />
	while(!valid) {<br />
		cout << "Please enter a number: ";<br />
		cin >> test;<br />
<br />
		if (!cin.fail())<br />
			valid = true;<br />
		else {<br />
			cin.clear();<br />
			cin >> dump;  //clear input buffer<br />
		}<br />
<br />
		if (valid && (test < 1  ||  test > 12)) {<br />
			valid = false;<br />
			cout << "Out of range" << endl;<br />
		}<br />
			<br />
	}<br />
	cout << "You entered " << test << endl;<br />

PS: how does everyone get code to not remove all spacing?

earl

-- modified at 14:53 Wednesday 12th July, 2006

Harold_Wishes12-Jul-06 10:04

12-Jul-06 10:04

I think this code below compiles. I only reformatted. I shortened the logic in the program as suggested and it works. The only problem I'm having is duplicate output (something I encountered last week). Below the user is prompted to enter data twice in sequence. The first time the user is prompted to make a selection from a menu screen (no big deal).

But, after the user hits the ENTER key, the user will see duplicates of the second prompt. It is as if the user hit the enter key twice.

How do I prevent this from happening? Better question . . . Why is it happening?

I know the compiler is taking me thru the while loop an extra time which is printing the duplicate prompt (confirmed by the debugger). Frown | :(

#include <cstring>
#include <string>
#include <iostream>


using namespace std;



int main()
{
    int data2;
    char buff[1024];
    unsigned int value;
    int charsRead; 

    char selection;
    cout << "A) Complete  B) Partial  C) UNKNOWN" << endl;
    cin >> selection;



    bool validEntry = false;
	while (!validEntry)
	{ 
		cout << "Please enter the number of subunits: ";
		cin.getline(buff, 1023, '\n');

		if (sscanf(buff, "%u%n",&value,&charsRead)==1 && value >=1 && value <= 12)
		   validEntry = true;
	}

	data2 = value;

  return 0;

}

-- modified at 21:56 Wednesday 12th July, 2006

pthread

mehmetned12-Jul-06 4:55

mehmetned

12-Jul-06 4:55

I include pthread.h but the compiler produced an error which was ( fatal error C1083: Cannot open include file: 'pthread.h': No such file or directory) why was this error produced?

toxcct12-Jul-06 4:58

toxcct

12-Jul-06 4:58

pthread is a header you wrote ?

i doubt it exists on visual C++ compiler.

aren't you compiling a source you found on the internet with a wrong compiler ?

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

led mike12-Jul-06 5:02

led mike

12-Jul-06 5:02

toxcct wrote:
pthread is a header you wrote

No it's Posix thread library ported to Win32 i think by Cygnus

"Just about every question you've asked over the last 3-4 days has been "urgent". Perhaps a little planning would be helpful?"
Colin Angus Mackay in the C# forum

led mike

David Crow12-Jul-06 4:58

12-Jul-06 4:58

mehmetned wrote:
why was this error produced?

Because the preprocessor could not find the file.

"The largest fire starts but with the smallest spark." - David Crow

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

led mike12-Jul-06 5:05

led mike

12-Jul-06 5:05

You need to make sure the compiler can "see" the files from the library. In the IDE usually under the Tools/Options menu item you can find the VC++ Directory settings. You probably need to add the paths to the library in those settings.

"Just about every question you've asked over the last 3-4 days has been "urgent". Perhaps a little planning would be helpful?"
Colin Angus Mackay in the C# forum

led mike

overzealous protection rules

Jun Du12-Jul-06 5:08

Jun Du

12-Jul-06 5:08

It's a header file for a POSIX thread library. Where is your code from? POSIX threads have been implemented on Unix, Linux and Windows. Try to figure out what POSIX library yous code was using.

Best,
Jun

Dave Schumann12-Jul-06 4:53

Dave Schumann

12-Jul-06 4:53

The following doesn't compile:

struct A
{
A* partner;

void doodah()
{ ++partner->value; } //this is legal
protected:
int value;
};

struct B: public A
{
void foobar()
{ partner->value += 2; } //but this isn’t
};

The complaint is that foobar() can't access A::value. But B is an A and A can access the value member of another A. So why can't B - which IS AN A - access the value member of another A?

--Dave Schumann

toxcct12-Jul-06 4:56

toxcct

12-Jul-06 4:56

i really don't see anything wrong in the code (except the doodah() method is a little dirty, but anyway).

what does the compiler say exactly (code + message) ?

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Dave Schumann12-Jul-06 5:02

Dave Schumann

12-Jul-06 5:02

FILENAME.cpp(230) : error C2248: 'A::value' : cannot access protected member declared in class 'A'
FILENAME.cpp(224) : see declaration of 'A::value'
FILENAME.cpp(218) : see declaration of 'A'

line 230 is the "partner->value += 2" call in foobar(). It has no complaint about the "++partner->value" call in doodah().

I'm not a language lawyer but this seems like it should be legal.

Dave Kerr12-Jul-06 4:59

Dave Kerr

12-Jul-06 4:59

It may be that you are trying to implement class like behaviour using structs.

Try this:

struct A
{
// Let the compiler know that B can access A's protected members.
friend struct B;

A* partner;

void doodah()
{ ++partner->value; } //this is legal
protected:
int value;
};

Dave Kerr
codechamber@hotmail.com
http://www.codechamber.com

Christian Graus12-Jul-06 5:00

Christian Graus

12-Jul-06 5:00

But a class *is* a struct.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

toxcct12-Jul-06 5:05

toxcct

12-Jul-06 5:05

Christian Graus wrote:
But a class *is* a struct.

hum, yes, but i would have said here that a struct *is* a class Roll eyes | :rolleyes:

only a matter of point of view Smile | :)

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]