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Old 03-08-2004, 06:34 PM   #1
miguetoo
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Registered: Mar 2003
Location: soCal..
Distribution: lfs server.. slackware workstation..
Posts: 58

Rep: Reputation: 15
strcmp.. ways to make it work..


hi.. i've got my program slightly finished.. it needs to have one function do a compare of a member of a struct but not sure how it's done.. i've been fiddling with this all night last night.. so here is the code..

this is the entire source..
Code:


#include <iostream.h>

#include <fstream.h>

#include <assert.h>

#include <string.h>

//#include <conio.h>

//#include <stdlib.h>



struct Listnode // i cannot edit structures; this is a given..

{

	char lastname[30];

	char firstname[30];

	int age;

};



struct Listtype

{

	Listnode * person[30];

	int size;

};



void initialize (Listtype &List);

void fillList (Listtype &List);

void printList (Listtype &List);

void doInsert (Listtype &List);

void doDelete (Listtype &List);

int menu (void);



main() // i cannot edit main function; this is a given..

{

	Listtype List;

	int choice;

	initialize (List);

	do

	{

//		system("cls"); it clears output.. this is included in menu() instead

		choice = menu();

		switch (choice)

		{

			case 1: fillList(List); break;

			case 2: printList(List); break;

			case 3: doInsert(List); break;

			case 4: doDelete(List); break;

			case 5: break;

			default: cout << "\nINVALID... 1-5 ONLY!\n";

				cin.ignore();

				cin.ignore();

		}

	}

	while (choice != 4);

}



int menu (void)

{

	int choice;

	cout << "\nMENU FOR LAB1\n";

	cout << "1. Fill the list from file laba1data.txt\n";

	cout << "2. Print the list (include the size of the list)\n";

	cout << "3. Insert a record into the list\n";

	cout << "4. Delete a record from the list\n";

	cout << "5. Quit\n\n";

	cout << "ENTER YOUR CHOICE: ";

	cin >> choice;

//	clrscr();

//	system("cls");

	return choice;



}



void initialize (Listtype &List)

{

	for (int i=0; i<30; i++)

	{

		List.person[i]=NULL;

	}

}



void fillList (Listtype &List)

{

	char firstname[30], lastname[30];

	int age, i=0;

	List.size=0;

	ifstream infile ("/home/school/laps/csit536/lab1data.txt", ios::in);

	assert (!infile.fail());



	while (infile>>lastname)

	{

		infile>>firstname;

		infile>>age;

		List.person[i] = new Listnode;

		strcpy(List.person[i]->lastname, lastname);

		strcpy(List.person[i]->firstname, firstname);

		List.person[i]->age=age;

		i++;

	}

	List.size=i;



}



void printList (Listtype &List)

{

	int i;

	for (i=0; i<List.size; i++)

		cout << i+1 << " " << List.person[i]->lastname << " " << List.person[i]->firstname << " " << List.person[i]->age << endl;

	cout << "\nSize of list= " << List.size << endl;

	return;

}



void doInsert (Listtype &List)

{

	char lastname[30], firstname[30];

	int positioninsert, inserted, age;

	cout << "Enter a record in this format: LASTNAME <SPACE> FIRSTNAME <SPACE> AGE \n";

	cin >> lastname >> firstname >> age;

	cout << "Insert this record at what position: ";

	cin >> positioninsert;

	inserted = positioninsert - 1;

// inserted is the position of inserted in the array

	List.size++;

	for ( ;positioninsert<List.size; positioninsert++)

		List.person[positioninsert]=List.person[inserted];

// count how many times List.person is bumped down for insert.. positioninsert is incremented for further bumping in longer lists

	List.person[inserted] = new Listnode;

	strcpy(List.person[inserted]->lastname, lastname);

	strcpy(List.person[inserted]->firstname, firstname);

	List.person[inserted]->age = age;

}



void doDelete (Listtype &List)

{

	char lastname[30], firstname[30];

//	Listtype todelete;

	int i=0, positionremove;

	cout << "Enter the name of the record to delete: ";

	cin >> lastname >> firstname;

	cout << "lastname is " << lastname << " and firstname is " << firstname << endl;

	cout << "List.person[i]->lastname is " << List.person[i]->lastname << " and List.person[i]->firstname is " << List.person[i]->firstname << endl;

	for (i; i<List.size; i++)

	{

//		if (lastname == List.person[i]->lastname && firstname == List.person[i]->firstname)

		if (strcmp(lastname, List.person[i]->lastname) && strcmp(firstname, List.person[i]->firstname)) 

		{

			positionremove = i;

			cout << "position remove is executed" << endl;

			for (i; i<List.size; i++)

			{

				List.person[i]=List.person[i+1];

			}

			break;

		}

		else if (i=List.size)

		{

			cout << "NAME NOT IN LIST" << endl;

			cout << "Hit return to continue" << endl;

		}

	}

	delete List.person[positionremove];

	List.size--;

}
this part is where i'm stuck..
Code:
void doDelete (Listtype &List)

{

	char lastname[30], firstname[30];

//	Listtype todelete;

	int i=0, positionremove;

	cout << "Enter the name of the record to delete: ";

	cin >> lastname >> firstname;

	cout << "lastname is " << lastname << " and firstname is " << firstname << endl;

	cout << "List.person[i]->lastname is " << List.person[i]->lastname << " and List.person[i]->firstname is " << List.person[i]->firstname << endl;

	for (i; i<List.size; i++)

	{

//		if (lastname == List.person[i]->lastname && firstname == List.person[i]->firstname) // this method doesn't work..

		if (strcmp(lastname, List.person[i]->lastname) && strcmp(firstname, List.person[i]->firstname)) 
// so does this method..
		{

			positionremove = i;

			cout << "position remove is executed" << endl;

			for (i; i<List.size; i++)

			{

				List.person[i]=List.person[i+1];

			}

			break;

		}

		else if (i=List.size)

		{

			cout << "NAME NOT IN LIST" << endl;

			cout << "Hit return to continue" << endl;

		}

	}

	delete List.person[positionremove];

	List.size--;

}
i just want the if statement to execute if lastname & firstname == List.person[i]->lastname & List.person[i]->firstname, respectively..

i've tried outputing the value and it comes out right but the if statement doesn't execute.. help..?
 
Old 03-08-2004, 07:13 PM   #2
llama_meme
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Registered: Nov 2001
Location: London, England
Distribution: Gentoo, FreeBSD
Posts: 590

Rep: Reputation: 30
strcmp returns 0 (false) if the strings are equal, so I think you might want
Code:
if(! strcmp(...)) { ... }
Alex
 
  


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