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Search found 6 results on 1 pages for 'devano1'.

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• pointers to functions

  - by DevAno1

  I have two basic Cpp tasks, but still I have problems with them. First is to write functions mul1,div1,sub1,sum1, taking ints as arguments and returning ints. Then I need to create pointers ptrFun1 and ptrFun2 to functions mul1 and sum1, and print results of using them. Problem starts with defining those pointers. I thought I was doing it right, but devcpp gives me errors in compilation. #include <iostream> using namespace std; int mul1(int a,int b) { return a * b; } int div1(int a,int b) { return a / b; } int sum1(int a,int b) { return a + b; } int sub1(int a,int b) { return a - b; } int main() { int a=1; int b=5; cout << mul1(a,b) << endl; cout << div1(a,b) << endl; cout << sum1(a,b) << endl; cout << sub1(a,b) << endl; int *funPtr1(int, int); int *funPtr2(int, int); funPtr1 = sum1; funPtr2 = mul1; cout << funPtr1(a,b) << endl; cout << funPtr2(a,b) << endl; system("PAUSE"); return 0; } 38 assignment of function int* funPtr1(int, int)' 38 cannot convertint ()(int, int)' to `int*()(int, int)' in assignment Task 2 is to create array of pointers to those functions named tabFunPtr. How to do that ?

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• dynamically created arrays

  - by DevAno1

  My task consists of two parts. First I have to create globbal char array of 100 elements, and insert some text to it using cin. Afterwards calculate amount of chars, and create dedicated array with the length of the inputted text. I was thinking about following solution : char[100]inputData; int main() { cin >> inputData >> endl; int length=0; for(int i=0; i<100; i++) { while(inputData[i] == "\0") { ++count; } } char c = new char[count]; Am I thinking good ? Second part of the task is to introduce in the first program dynamically created array of pointers to all inserted words. Adding a new word should print all the previous words and if there is no space for next words, size of the inputData array should be increased twice. And to be honest this is a bit too much for me. How I can create pointers to words specifically ? And how can I increase the size of global array without loosing its content ? With some temporary array ?

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• How the JOptionPane works

  - by DevAno1

  How can I control what happens with window after clicking JOPtionPane buttons ? I'm trying to implement simple file chooser. In my frame I have 3 buttons (OK, Cancel, Browse). Browse button opens file search window, and after picking files should return to main frame. Clicking OK will open a frame with the content of the file. Now porblem looks this way. With the code below, I can choose file but directly after that a new frame is created, and my frame with buttons dissapears : import java.io.File; import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; import java.awt.*; import javax.swing.*; import java.io.*; public class Main { public static void main(String args[]) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { show("Window"); } }); } public static void show(String frame_name){ JFrame frame = new JFrame(frame_name); frame.setPreferredSize(new Dimension(450, 300)); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel top = new JPanel(); top.setLayout(new BoxLayout(top, BoxLayout.Y_AXIS)); JFileChooser fc = new JFileChooser(new File(".")); JPanel creator = new JPanel(); creator.setLayout(new BoxLayout(creator, BoxLayout.Y_AXIS)); creator.add(top); String[] buttons = {"OK", "Cancel", "Browse"}; int rc = JOptionPane.showOptionDialog( null, creator, frame_name, JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null, buttons, buttons[0] ); String approveButt = ""; switch(rc){ case 0: break; case 1: break; case 2: approveButt = buttons[rc]; int retVal = fc.showDialog(null, approveButt); if (retVal == JFileChooser.APPROVE_OPTION) System.out.println(approveButt + " " + fc.getSelectedFile()); break; } frame.pack(); frame.setVisible(true); } } With the second code I can return to my menu, but in no way I am able to pop this new frame, which appeared with first code. How to control this ? What am I missing ? public class Main { public static void main(String args[]) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { show("Window"); } }); } public static void show(String frame_name){ JFrame frame = new JFrame(frame_name); frame.setPreferredSize(new Dimension(450, 300)); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel top = new JPanel(); top.setLayout(new BoxLayout(top, BoxLayout.Y_AXIS)); JFileChooser fc = new JFileChooser(new File(".")); JPanel creator = new JPanel(); creator.setLayout(new BoxLayout(creator, BoxLayout.Y_AXIS)); creator.add(top); String[] buttons = {"OK", "Cancel", "Browse"}; String approveButt = ""; Plane m = null; int rc = -1; while (rc != 0) { rc = JOptionPane.showOptionDialog( null, creator, frame_name, JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null, buttons, buttons[0] ); switch (rc) { case 0: m = new Plane(); case 1: System.exit(0); case 2: approveButt = buttons[rc]; int retVal = fc.showDialog(null, approveButt); if (retVal == JFileChooser.APPROVE_OPTION) System.out.println(approveButt + " " + fc.getSelectedFile()); break; default: break; } } addComponents(frame.getContentPane(), m); frame.pack(); frame.setVisible(true); } private static void addComponents(Container c, Plane e) { c.setLayout(new BoxLayout(c, BoxLayout.Y_AXIS)); c.add(e); } } class Plane extends JPanel { public Plane(){ } @Override public void paint(Graphics g){ g.setColor(Color.BLUE); g.fillRect(0, 0, 400, 250); } }

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• Cpp some basic problems

  - by DevAno1

  Hello. My task was as follows : Create class Person with char*name and int age. Implement contructor using dynamic allocation of memory for variables, destructor, function init and friend function show. Then transform this class to header and cpp file and implement in other program. Ok so I've almost finished my Person class, but I get error after destructor. First question is how to write this properly ? #include <iostream> using namespace std; class Person { char* name; int age; public: int * take_age(); Person(){ int size=0; cout << "Give length of char*" << endl; cin >> size; name = new char[size]; age = 0; } ~Person(){ cout << "Destroying resources" << endl; delete *[] name; delete * take_age(); } friend void(Person &p); int * Person::take_age(){ return age; } void init(char* n, int a) { name = n; age = a; } void show(Person &p){ cout << "Name: " << p.name << "," << "age: " << p.age << endl; } }; int main(void) { Person *p = new Person; p->init("Mary", 25); p.show(); system("PAUSE"); return 0; } And now with header/implementation part : - do I need to introduce constructor in header/implementation files ? If yes - how? - my show() function is a friendly function. Should I take it into account somehow ? I already failed to return this task on my exam, but still I'd like to know how to implement it.

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• Complicated conditional SQL query

  - by DevAno1

  I'm not even sure if it's possible but I need it for my Access database. So I have following db structure : Now I need to perform a query that takes category_id from my product and do the magic : - let's say product belongs to console (category_id is in table Console) - from console_types take type_id, where category_id == category_id - but if product belongs to console_game (category_id is in table console_game) - from console_game take game_cat_id, where category_id == category_id I'm not sure if mysql is capable of such thing. If not I'm really f&%ranked up. Maybe there is a way to split this into 2,3 separate queries ?

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• Simple 'database' in c++

  - by DevAno1

  Hello. My task was to create pseudodatabase in c++. There are 3 tables given, that store name(char*), age(int), and sex (bool). Write a program allowing to : - add new data to the tables - show all records - sort tables with criteria : - name increasing/decreasing - age increasing/decreasing - sex Using function templates is a must. Also size of arrays must be variable, depending on the amount of records. I have some code but there are still problems there. Here's what I have: Function tabSize() for returning size of array. But currently it returns size of pointer I guess : #include <iostream> using namespace std; template<typename TYPE> int tabSize(TYPE *T) { int size = 0; size = sizeof(T) / sizeof(T[0]); return size; } How to make it return size of array, not its pointer ? Next the most important : add() for adding new elements. Inside first I get the size of array (but hence it returns value of pointer, and not size it's of no use now :/). Then I think I must check if TYPE of data is char. Or am I wrong ? // add(newElement, table) template<typename TYPE> TYPE add(TYPE L, TYPE *T) { int s = tabSize(T); //here check if TYPE = char. If yes, get the length of the new name int len = 0; while (L[len] != '\0') { len++; } //current length of table int tabLen = 0; while (T[tabLen] != '\0') { tabLen++; } //if TYPE is char //if current length of table + length of new element exceeds table size create new table if(len + tabLen > s) { int newLen = len + tabLen; TYPE newTab = new [newLen]; for(int j=0; j < newLen; j++ ){ if(j == tabLen -1){ for(int k = 0; k < len; k++){ newTab[k] = } } else { newTab[j] = T[j]; } } } //else check if tabLen + 1 is greater than s. If yes enlarge table by 1. } Am I thinking correct here ? Last functions show() is correct I guess : template<typename TYPE> TYPE show(TYPE *L) { int len = 0; while (L[len] == '\0') { len++; } for(int i=0; i<len; i++) { cout << L[i] << endl; } } and problem with sort() is as follows : Ho can I influence if sorting is decreasing or increasing ? I'm using bubble sort here. template<typename TYPE> TYPE sort(TYPE *L, int sort) { int s = tabSize(L); int len = 0; while (L[len] == '\0') { len++; } //add control increasing/decreasing sort int i,j; for(i=0;i<len;i++) { for(j=0;j<i;j++) { if(L[i]>L[j]) { int temp=L[i]; L[i]=L[j]; L[j]=temp; } } } } And main function to run it : int main() { int sort=0; //0 increasing, 1 decreasing char * name[100]; int age[10]; bool sex[10]; char c[] = "Tom"; name[0] = "John"; name[1] = "Mike"; cout << add(c, name) << endl; system("pause"); return 0; }

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