Pointer Problem

[The Hobo]

I wrote up this code for an assignment, but...I'm stuck:

#include <iostream>
#include <iomanip>
#include "people.h"
using namespace std;

int main(int argc, char *argv[]) {
	
	PEOPLE *paPeople = NULL;
	int iNumToEnter = 0;

	cout << "Number of people to enter: ";
	cin >> iNumToEnter;

	if (paPeople != NULL)	{
		exit(0);
	}

	paPeople = new PEOPLE[iNumToEnter];

	for (int i = 0; i < iNumToEnter; i++) {
		cout << "Person #" << (i + 1) << "'s Name: ";
		cin.ignore();
		cin >> paPeople->szName;

		cout << "Age of " << paPeople->szName << ": ";
		cin >> paPeople->age;
	}

	system("CLS");

	//SHWINK, problem here:
	for (int i = 0; i < iNumToEnter; i++) {
		cout << paPeople->szName << endl;
	}
	
	return 0;
}

Any ideas?

[transcendental]

#include <iostream>
#include <iomanip>
#include "people.h"
using namespace std;

int main(int argc, char *argv[]) {
	
	PEOPLE *paPeople = NULL;
	int iNumToEnter = 0;

	cout << "Number of people to enter: ";
	cin >> iNumToEnter;

	if (paPeople != NULL)	{
		exit(0);
	}

	paPeople = new PEOPLE[iNumToEnter];

	for (int i = 0; i < iNumToEnter; i++) {
		cout << "Person #" << (i + 1) << "'s Name: ";
		cin.ignore();
		cin >> paPeople[i].szName;

		cout << "Age of " << paPeople->szName << ": ";
		cin >> paPeople[i].age;
	}

	system("CLS");

	//SHWINK, problem here:
	for (int i = 0; i < iNumToEnter; i++) {
		cout << paPeople[i].szName << endl;
	}
	
	return 0;
}

[transcendental]

You forgot to delete the pointer.

delete [] paPeople ;

And what does this code do?

if (paPeople != NULL){
exit(0);
}

[The Hobo]

Originally posted by transcendental
And what does this code do?

if (paPeople != NULL){
  exit(0);
}

Hell if I know. Just something my teacher insists on us doing. Making sure the pointer is NULL before and after it's "newed."

[CornedBee]

Your teacher needs a good spanking. Making sure it's not NULL after allocating is good. Making sure it's NULL before allocating is a stupid waste.

[The Hobo]

Originally posted by CornedBee
Your teacher needs a good spanking. Making sure it's not NULL after allocating is good. Making sure it's NULL before allocating is a stupid waste.

After he assigns me a grade at the end of the semester, I'll be sure to inform him of that.

I'll ask him and see what his reasoning is, though.

[transcendental]

It occurred to me it may be better for you to use this form, so that it is clear to you that you are actually using a pointer (which is to be deleted later.)

Use

(paPeople+i)->blahblah

instead of

paPeople[i].blahblah

[kedaman]

arrays are pointers

[The Hobo]

Now I'm stuck with this:

int main() {
	
    PEOPLE *paPeople[100] = {NULL};
    int iNumToEnter = 0;

    //...

    for (int i = 0; i < iNumToEnter; i++) {
        paPeople[i] = new PEOPLE;
	
	//...

	cout << "Person #" << (i + 1) << "'s Name: ";
	cin.ignore();
	cin.getline(paPeople[i].szName, 25);

	//...
    }

    //...
}

[kedaman]

paPeople[i] is a pointer to PEOPLE, thus use select dereferenced pointer -> instead of .
why do you need indirection here anyway?

[CornedBee]

Why is the class called PEOPLE when each instance represents a single person? Just wondering...

[transcendental]

Different from your first posting, now you are using an array of pointers, instead of pointer to an array.

Originally posted by The Hobo
Now I'm stuck with this:

int main() {
	
    PEOPLE *paPeople[100] = {NULL};
    int iNumToEnter = 0;

    //...

    for (int i = 0; i < iNumToEnter; i++) {
        paPeople[i] = new PEOPLE;
	
	//...

	cout << "Person #" << (i + 1) << "'s Name: ";
	cin.ignore();
	cin.getline(paPeople[i].szName, 25);

	//...
    }

    //...
}

So you should do it this way

int main() {
	
    PEOPLE *paPeople[100] = {NULL};
    int iNumToEnter = 0;

    //...

    for (int i = 0; i < iNumToEnter; i++) {
        paPeople[i] = new PEOPLE;
	
	//...

	cout << "Person #" << (i + 1) << "'s Name: ";
	cin.ignore();
	cin.getline(paPeople[i]->szName, 25);

	//...
    }

    //...
}

I hope you are not confused.

[The Hobo]

Thanks