How can I use 2D array in C++ using Visual Studio? - c++

I'm new to this site and programming in C++ language this semester.
I have been really trying for 2 days and have asked classmates but they do not know either. A classmate said to use the 2D arrays but I don't know what that is and my professor has not gone over 2D arrays.
I am stuck and would really appreciate help.
The input file contains this:
Plain_Egg 1.45
Bacon_and_Egg 2.45
Muffin 0.99
French_Toast 1.99
Fruit_Basket 2.49
Cereal 0.69
Coffee 0.50
Tea 0.75
idk how to display all the "users" orders
Basically a receipt, like he orders this and how many, then ask "u want anything else?", then take the order number and how many again, THEN at the end give back a receipt that looks like this
bacon_and_eggs $2.45
Muffin $0.99
Coffee $0.50
Tax $0.20
Amount Due $4.14
Here is my code:
// Libraries
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
#include <cmath>
using namespace std;
//structures
struct menuItemType {
string itemName;
double itemCost;
};
// Prototypes
void header();
void readData(menuItemType menu[]);
void Display(menuItemType menu[]);
int main() {
header();
menuItemType menu [8];
readData(menu);
Display(menu);
//system("pause");
return 0;
}
void header() {
char c= 61;
for (int i=0; i < 64; i++) {
cout << c;
}
cout << c << endl;
cout << endl;
cout << "Breakfast Menu" <<endl;
for (int i=0; i < 64; i++) {
cout << c;
}
cout << "" << c << endl;
cout << endl;
}
void readData(menuItemType item[]) {
int i=0;
ifstream in;
in.open("input.txt");
cout << fixed << setprecision(2);
while(!in.eof()) {
in >> item[i].itemName >> item[i].itemCost;
++i;
}
}
void Display(menuItemType item[]) {
int choice = 0, quantity = 0;
double total = 0.0, totalF = 0.0, tax = 0.0;
char exit = 'y';
int j = 1, z = 1, i = 1;
//the Menu
for (int i=0; i<8; i++){
cout << j << ". " << setw(18) << left << item[i].itemName << "$" << setw(10) << item[i].itemCost << endl;
j++;
}
cout << endl;
while(exit == 'y' || exit == 'Y') {
cout << "Please Enter your Selection or 0 to Exit : ";
cin >> choice;
if(cin.fail()) {
cout << "*******Invalid selection*******" << endl;
cin.clear();
cin.ignore(1000,'\n');
} else if (choice==0) {break; }
else {
cout<< "Enter Quantity: ";
cin>> quantity;
if (quantity==0) { break;}
else {
choice--;
total += (quantity * item[choice].itemCost);
tax = (total * .05);
totalF = total + tax;
cout << endl;
}
cout << endl;
cout << "======================================================" << endl;
cout << item[choice].itemName << "\t\t" << item[choice].itemCost << endl;
cout << "======================================================" << endl;
cout << "Do you want to continue (Y/N): ";
cin >> exit;
}
}
}

First off, you don't need a two dimensional array for this! You already have a one dimensional array of a suitable structure, as far as I can tell: Something which stores the name of the object and its price. What is somewhat missing is how many objects are currently in the array and how much space it has. If you want to go with the content of the entire array, make sure that you objects are correctly initialized, e.g., that the names are empty (this happens automatically, actually) and that the prices are zero (this does not).
I'm not sure if it is a copy&paste errors but the headers are incorrectly included. The include directives should look something like this:
#include <iostream>
The actual loop reading the values doesn't really work: You always need to check that the input was successful after you tried to read! Also, using eof() for checking that the loop ends is wrong (I don't know where people pick this up from; any book recommending the use of eof() for checking input loops is only useful for burning). The loop should look something like this:
while (i < ArraySize && in >> item[i].itemName >> item[i].itemCost)
++i;
}
This also fixes the potential boundary overrun in case there is more input than the array can consume. You might want to consider using a std::vector<Item> instead: this class keeps track of how many elements there are and you can append new elements as needed.
Note that you didn't quite say what you are stuck with: You'd need to come up with a clearer description of what your actual problem is. The above is just correcting existing errors and readjusting the direction to look into (i.e., forget about two dimensional arrays for now).

Related

How to add numbers bigger than long long, long, int and etc C+11

forum!
I have a project where we are supposed to add numbers that are length 14 or greater. I did some digging and realized that there is no current type that takes numbers this big. So, I have the user enter the numbers as a string and the numbers they would like to add are stored in a static string array.
I would like to add the numbers from the static array together. The issue is I have no idea how to deal with numbers this large. I am assuming you would have to convert the string values into int's and add them up one by one? I am having a big issue coming up with the logic for this. Any help would be appreciated.
If not, if you can provide some context which could help me come up with some logic.
The only library functions I can use is iostream and string.
Here is my code if you'll like to see my logic! I have some test cases I am trying to figure out so please ignore the comment outs. But, if you run the code you should get a better sense of what I am trying to get out. I am trying to sum up the numbers the user enters.
#include <iostream>
#include <string>
using namespace std;
void amountOfNumbers(string &userAmount, int MIN_AMOUNT, int MAX_AMOUNT){
//string alpha = "abcdefghijklmnopqrstuvwxyz";
cout << "How many numbers? -> ";
cin >> userAmount;
cout << endl;
while(!userAmount.find("abcdefghijklmnopqrstuvwxyz")){
cout << "ERROR: must be a number, try again ->";
cout << userAmount;
//cin.clear();
//cin.ignore(1000, '\n');
cin >> userAmount;
cout << endl;
}
int temp = stoi(userAmount);
while((temp < MIN_AMOUNT) or (temp > MAX_AMOUNT)){
cout << "ERROR: Program can only take in " << MIN_AMOUNT << " - "<< MAX_AMOUNT << " numbers. Try again ->";
cin >> userAmount;
cout << endl;
temp = stoi(userAmount);
}
}
void takeNumbers(string &userAmount, string (&numberArray)[11]){
int temp = stoi(userAmount);
for (int i = 0; i < temp; i++){
cout << "Input number #" << i+1 << " ->";
cin >> numberArray[i];
cout << endl;
}
}
void display(string &userAmount, string (&numberArray)[11]){
int temp = stoi(userAmount);
for (int i = 0; i < temp; i++){
cout << numberArray[i];
cout << endl;
}
}
void addNumber(string &userAmount, string (&numberArray)[11]){
}
int main() {
const int MIN_AMOUNT = 2, MAX_AMOUNT = 11, MAX_INPUT = 14;
string userAmount = "0";
string numberInput;
// static array
string numberArray [MAX_AMOUNT];
amountOfNumbers(userAmount, MIN_AMOUNT, MAX_AMOUNT);
takeNumbers(userAmount, numberArray);
display(userAmount, numberArray);
}

printing name in multiple for loops and arrays

I've come across a little problem, how do I print the winning candidate's name? See the instructions here are, input five names, their number of votes and percentage of votes, whoever has the highest wins. I don't know if I did my code right, but it works.. well except for the name part. I've tried everything from a lot of for loops to transfer the array or what.
I'm almost done with the code.
Here's the code
#include <iostream>
#include <stdio.h>
using namespace std;
int main()
{
char candidates[50];
int votes[5]={0};
float percent[5]={0};
int a,b,c,d,e,i;
int maxx;
int champ=0;
char winner[50];
cout << "Enter the candidates' last names: ";
cout << endl;
for(a=1;a<=5;a++)
{
cout << a << ". ";
cin >> candidates;
}
cout << endl;
cout << "Enter their number of votes: " << endl;
for(b=1;b<=5;b++)
{
cout << b << ". ";
cin >> votes[b];
}
cout << endl;
cout << "percentage of votes: " << endl;
for(c=1;c<=5;c++)
{
cout << c << ". ";
percent[c]=votes[c]*0.2;
printf("%.2f\n", percent[c]);
}
cout <<"Candidates\t\tVotes\t\t% of Votes" << endl;
for(int k=1;k<=5;k++)
{
cout << candidates[k] << "\t\t\t" << votes[k] << "\t\t\t";
printf("%.2f\n", percent[k]);
}
maxx=percent[0];
for(d=1;d<=5;d++)
{
if(maxx<percent[d]);
{
//what happens here?
}
}
return 0;
}
You should keep a 2d array of characters or array of string for storing candidate names instead of a 1-d array.
char candidates[5][10]; //
for(int i = 0; i < 5; i++)
{
cin >> candidates[i];
}
Then keep a variable to store index for winning candidate
int winIndex = 0;
int winPercent = 0;
for(int i = 0; i < 5; i++)
{
if(percent[i] > winPercent)
{
winPercent = percent;
winIndex = i;
}
}
Finally print name of winning candidate;
cout << candidates[winIndex];
In object oriented approach, you may create a class with following information
class Candidate
{
string name;
int votes;
float percent;
};
Use string candidates[50]; instead of char candidates[50];
then cin >> candidates[a];

C++ Array parameters and const value

I do not get arrays, Im sure there are easier ways to make this program but I must do it the teacher's way and I am lost.
This is the assigment:
I do not get how I should go about these arrays. most confusing thing I seen by far.
What I would like is a guide or help on how i should program these arrays or how I should program arrays period. Not asking to do the rest for me, I already know how to do most of this, its just the arrays I like to know how to do.
This is my current program:
#include<iostream>
using namespace std;
void getPoints(int pPossible[], double pEarned[], int numItems, int limit);
int sumArray(double
void getpoints(int pPossible[], double pEarned[], int numItems, int limit)
{
int count;
while (limit == limit)
{
cout << "Input grade points for a category in the gradebook: " << endl
<< "How many items available in the category?: ";
cin >> numItems;
cout << endl;
if(numbItems > limit)
{
cout << "The Value exceeds the maximum number of items." << endl;
continue;
}
break;
}
count=1;
for(count=1; count<numItems; count++)
cout << "Enter points then points possible for Item " << count << ": ";
cin << pEarned[count] << pPossible[count];
return 0;
}
C++ array indexes are zero-based, so you should use zero for the initial value in the for loop. Also, you're missing the braces for the for loop body; as it is, it will run the cout line numItem-1 times and the cin line just once.
Another thing: the operators in the for's cin line should be >>, not <<. You want input here, not output.
Finally, like #ebyrob said, make numItems a reference parameter (it would be clearer for the caller to use a pointer instead, but the assignment asked for a reference parameter).
void getpoints(int pPossible[], double pEarned[], int& numItems, int limit)
{
//Read number of items
while (true)
{
cout << "Input grade points for a category in the gradebook: " << endl
<< "How many items available in the category?: ";
cin >> numItems;
cout << endl;
if(numItems >= limit)
{
cout << "The Value exceeds the maximum number of items." << endl;
continue;
}
break;
}
//Read earned and possible for each item
for(int count=0; count<numItems; count++)
{
cout << "Enter points then points possible for Item " << count << ": ";
cin >> pEarned[count] >> pPossible[count];
}
return 0;
}

How do I use cin in a while loop?

I'm trying to get the user to input their name(s) using a while loop with an array and cin, but after the last person's name is input, the program crashes instead of moving on. Is there a way to fix this, or do I need to completely change up the code? I'm also fairly new to c++, so can any answers be given as simply as possible?
#include <iostream>
#include <string>
using namespace std;
int main()
{
unsigned int numberofplayers;
number://loop back here if more than 4 players
cout << "Number of players: ";
cin >> numberofplayers;
if(numberofplayers > 4 || numberofplayers < 1){
cout << "Invalid number, please enter a number from 1 to 4." << endl;
goto number;
}
string name[numberofplayers];
cout << "Enter your name" << endl;
int a = 1;
while(a < numberofplayers + 1){
cout << "Player " << a << ": ";
cin >> name[a];
cout << "Hello, " << name[a] << "." << endl;
a++;
}
}
You would probably facing array index out of bound, so Change you while loop to this and set a=0 to fill from 0th index.
while(a < numberofplayers){
}
Your last iteration exceeds the size of the array. You need to change it to
while(a < numberofplayers)
also, on another note, the keyword goto isn't used much anymore. I would suggest using a while there also like
while(true){
cout<<"number of players";
cin>>numberofplayers
if(numberofplayers is valid input){
break;
}
cout<<"bad input";
}
There is a question on stackoverflow discussing the use of goto extensively here:
GOTO still considered harmful?

How to use a dynamically sized array of structs?

I have to make my homework. It is console application which uses an array of structs that keep information about a computer(brand, year of manufactoring, weight and inventory number). So I wrote a completely working program, but I want to use a dynamic array, because I dont know how many records the user will input.
Is there way to do this. To add new records in array until the user say n/N? Any suggestions?
This is my version of program:
#include "stdafx.h"
#include <iostream>
using namespace std;
struct ComputerInfo
{
char computerMark[20], invertarNumber[6];
unsigned int year;
float weight;
};
ComputerInfo computerArray[300];
ComputerInfo AddComputers(ComputerInfo compterArray[], int counter)
{
cout << "Enter mark of the computer: ";
cin >> computerArray[counter].computerMark;
cout << "Enter year of establish: ";
cin>> computerArray[counter].year;
while ((computerArray[counter].year < 1973)
|| (computerArray[counter].year > 2013))
{
cout << "INVALID YEAR!!!" << endl;
cout << "Enter year of establish: ";
cin>> computerArray[counter].year;
}
cout << "Enter computer weidth: ";
cin >> computerArray[counter].weight;
cout << "Enter computer invertar number(up to six digits): ";
cin >> computerArray[counter].invertarNumber;
return computerArray[counter];
}
void ShowRecords()
{
int counter = 0;
while (computerArray[counter].year != 0)
{
cout << "Mark: " << computerArray[counter].computerMark << endl;
cout << "Year: " << computerArray[counter].year << endl;
cout << "Weidth: " << computerArray[counter].weight << endl;
cout << "Inv. number: " << computerArray[counter].invertarNumber << endl << endl;
counter++;
}
}
void MoreThanTenYearsOld(ComputerInfo computerArray[])
{
int counter = 0;
float counterOldComputers = 0;
float computerPer = 0;
while (computerArray[counter].year == 0)
{
if (computerArray[counter].year <= 2003)
{
counterOldComputers++;
}
counter++;
}
computerPer = counterOldComputers / 3;
cout << endl;
cout << "Percantage of old computers is: " << computerPer << endl;
}
int main()
{
int counter = 0;
float computerPer = 0;
char answer = 'y';
for (int i = 0; i <= 299; i++)
{
strcpy(computerArray[i].computerMark,"");
}
while((answer == 'Y') || (answer == 'y'))
{
computerArray[counter] = AddComputers(computerArray, counter);
cout << endl;
cout << "Do you want to enter more records (Y/N): ";
cin >> answer;
cout << endl;
counter++;
}
MoreThanTenYearsOld(computerArray);
return 0;
}
Yes. Instead of your array, use
std::vector<ComputerInfo> computerArray;
and you can add as many objects as you want:
ComputerInfo c;
// read the data
computerArray.push_back(c);
now, computerArray[0] will have the info in c.
You'll need to #include <vector>.
Also, instead of char computerMark[20] you can use a std::string.
You have two options:
1) Use std::vector instead of an array. This is a very powerful tool and certainly worth learning how to use.
2) Dynamically allocate the array and resize it as you add more items. Basically this means writing your own version of std::vector. This is a good way to strengthen your programming skills. You will learn what goes into writing standard classes and functions. However, I advise using std::vector in more serious programming because it has already been thoroughly tested and debugged.