I am trying to build a 2D array which has dynamic dimensions. I could use the vector class for this, but my assignment prohibits it. So I came up with the following code :
#include <iostream>
using namespace std;
int main() {
cout << "1" << endl;
int** 2DArr = new int*[5];
cout << "2" << endl;
for(unsigned int index = 0; index < 5; index++)
{
2DArr[index] = new int[5];
cout << "3";
}
cout <<"\n4"<<endl;
for(int row = 0; row < 5; row++)
{
cout << "5 " << endl;
for(int col = 0; col < 5; col++)
{
cout << "6 " << endl;
2DArr[row][col] = 1;
cout << "7" << endl;
cout << 2DArr[row][col];
cout << "8" << endl;
}
cout << "8" << endl;
}
cout << "9" << endl;
}
The code above is an example of what I am trying to accomplish, along number at each step. The above code seems to hang right after "6" is printed. Can anyone explain to me why the above code doesn't work and how I could fix it? My understanding is that 2D arrays made of pointers can be accessed using [], yet for some reason, the above hangs at the exact line i'm trying to assign 1 to the 2D array. My guess is that it expects an adress and not an int, but I;m not sure. Please show me howto assign an actual integer at step 6.
Thank you very much.
Related
I am struggling with printing an array with 4 rows and 4 columns, when I initialized the array and entered all the values. Then, I used for loop to get all the values together so I can print them. But I get is an array that companied all the values in one row.
I have attached the output when I run the code.
Here is a portion of my code, it is long code but I am struggling in specific part:
#include <iostream>
using namespace std;
int main()
{
cout << "The martix before I flipped it: " << endl;
cout << endl;
int array[4][4] = { 16,3,2,13,5,10,11,8,9,6,7,12,4,5,14,1 };
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
cout << array[i][j] << " ";
}
}
return 0;
The standard output utility std::cout is a stream from the stl and, as such, its << operator does not usually automagically append a linebreak.
Which is quite practical since, otherwise, you would not be able to print multiple numbers on a single line.
That being, said, you'll need to add the linebreak manually, like so :
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
std::cout << array[i][j] << " ";
}
std::cout << std::endl;
}
Alternatively, you can consider printing lines 4 at a time since your matrix is of constant size :
for (int i = 0; i < 4; i++) {
std::cout << array[i][0] << " "
<< array[i][1] << " "
<< array[i][2] << " "
<< array[i][3] << " " << std::endl;
}
Have a great day,
I have only a little experience in C++. I'm trying to write a program to print each element of the 'sales' array:
#include <iostream>
#include <iomanip>
using namespace std;
void printArray(int, int);
int main()
{
char chips[5][50] = {"mild", "medium", "sweet", "hot", "zesty"};
int sales[5] = {0};
int tempSales, counter;
const int i = 5;
for (counter = 0; counter < i; counter++)
{
cout << "Please enter in the sales for " << chips[counter] << ": ";
cin >> tempSales;
tempSales >> sales[counter][5];
}
cout << "{";
for (int counter = 0; counter < i; counter++)
{
cout << chips[counter] << ", ";
}
cout << "}" << endl;
cout << "{";
for (int counter = 0; counter < i; counter++)
{
cout << sales[counter] << ", ";
}
cout << "}" << endl;
return 0;
}
To solve this problem, I need to have the same commands and keywords I still have, and it can't be any advanced or weird syntax. For some reason, my input from the:
cin >> tempSales
Is not functioning. Here are the results:
{mild, medium, sweet, hot, zesty, }
{0,0,0,0,0, }
Whereas I just want to see 1, 2, 3, 4, and 5 for the second array. Why is it only print 0 and not reading my input? Please help!
Like rranjik stated, you shouldn't need a 2D array if you're only listing the number of sales, which it appears you're doing from what you provided, is this not the case?
Is it necessary for you to use the bitshift operator >> for your assignment? For a simple integer assignment it isn't really necessary, and you could do:
int sales[5] = {0}; Change the array to a simple array instead of 2D.
sales[counter] = tempSales; Use standard assignment for the integer on line 19
cout << sales[counter] << ", "; Change your output accordingly.
Hope this helps!
I don't think you need a 2D array for sales. Try cout << sales[counter][5] << ", "; or change int sales[5][6] = {0}; to int sales[5] = {0};. As Luke mentioned, use standard assignment sales[counter] = tempSales;.
I am a beginner in programming. I was doing some simple applications. I was already done with my programme when I realised that my variable is getting random, even if I set it to 0. I was trying to figure it out why. My goal is to add 1 to the "cor" variable when the answer is matching the random generated number, the "else" section is working as it has to be. Maybe someone more experienced can help me.
`
#include <iostream>
#include <string>
#include <time.h>
#include <Windows.h>
using namespace std;
int number;
int ynumber[5];
int cor = 0;
int falsed = 0;
int main()
{
cout << "Welcome to our lottery!" << endl;
cout << "We start in ..." << endl;
Sleep(2000);
for (int i = 3; i >= 0; i--)
{
system("cls");
cout << i << endl;
Sleep(1000);
}
system("cls");
srand(time(NULL));
for (int i = 0; i < 6; i++)
{
cout << "Type your " << i+1 << " number below" << endl;
cin >> ynumber[i];
number = rand() % 50 + 1;
cout << "The picked number is: " << number << endl;
Sleep(1000);
if (ynumber[i] == number)
{
cout << "Same same!" << endl;
cor = cor + 1;
}
else
{
cout << "Hope for better luck next time ;)" << endl;
falsed = falsed + 1;
}
}
system("cls");
cout << "Thank you for participating!" << endl << "Correct picked numbers: " << cor << endl << "Wrong picked numbers: " << falsed << endl << endl;
system("pause");
return 0;
}
`
int ynumber[5];
The length of your array is 5
for (int i = 0; i < 6; i++)
{
//...
cin >> ynumber[i];
You loop over the indices 0,1,2,3,4,5. Use your fingers to count the number of indices that you use. You'll notice that you access the array at 6 different fingers. 6 is more than 5. As such, we can conclude that you're accessing the array out of bounds. The consequence is that behaviour of your program is undefined.
Solution: Do not access an array out of bounds. The last index of array of length n is n - 1.
More generally: Don't rely on magic numbers. In this case, you could use instead:
for (int i = 0; i < std::size(ynumber); i++)
I am making a 20 questions game in C++ and have everything working, except for the displayWords function. The code I currently have keeps breaking. Any explanation would be appreciated! Thank you!
void displayWords()
{
int x = 0;
string words[50] = {"LCHS","Shark","Pencil","Pizza","New York","Fish","Car","Ice Cream","Los Angeles","Bird","Basketball","Fried Chicken",
"Dog","Tiger","Penguin","Plane","Rock","Barbecue Sauce","Mustard","Ketchup","Hot sauce","Peppers","Salt","Tacos","Shrimp","Pickels",
"Tomatos","Bannanas","Burger","Computer","Iphone","Motorcycle","Bicycle","Skateboard","Lightbulb","Golf Ball","Surfboard","Luggage",
"Rollercoaster","Cat","Lion","Cockroach","Grasshopper","Beach","Theme Park","Swimming Pool","Bowling Ally","Movie Theater","Golf Course","Shopping Mall"};
cout << "The following list of words are what the computer is capable of guessing" << endl;
cout << endl;
while(x < 50)
{
for (int y = 0; y <= 5; y++)
{
cout << words[x] << ", ";
if(x<50)
x++;
}
cout << endl;
}
}
I would like it to display the list of 50 words in an organized fashion.
By example, as:
for( int x = 0; x<sizeof(words)/sizeof(*words); x++ ) {
if( x%5==0 ) cout << endl; else cout << ", ";
cout << words[x];
}
take into account the problematic of the array's size calculation: see this link How do I find the length of an array?
If I understand correctly, you want your list displayed as 5 columns. Simplest way, use a nested for loop and proper formatting with std::setw (must #include <iomanip>):
for(size_t i = 0; i < 10; ++i)
{
for(size_t j = 0; j < 5; ++j)
{
std::cout << std::setw(20) << std::left << words[i * 5 + j];
}
std::cout << std::endl;
}
Your actual loop is incorrect, as it will lead to repetitions.
Maybe I'm not interpreting your question correctly but if you want to just print out the 50 words then you can use something like the code below. Not sure of the reason that the nested for loop iterating y was there.
Edit
void displayWords()
{
int x;
string words[50] = {"LCHS","Shark","Pencil","Pizza","New York","Fish","Car","Ice Cream","Los Angeles","Bird","Basketball","Fried Chicken",
"Dog","Tiger","Penguin","Plane","Rock","Barbecue Sauce","Mustard","Ketchup","Hot sauce","Peppers","Salt","Tacos","Shrimp","Pickels",
"Tomatos","Bannanas","Burger","Computer","Iphone","Motorcycle","Bicycle","Skateboard","Lightbulb","Golf Ball","Surfboard","Luggage",
"Rollercoaster","Cat","Lion","Cockroach","Grasshopper","Beach","Theme Park","Swimming Pool","Bowling Ally","Movie Theater","Golf Course","Shopping Mall"};
cout << "The following list of words are what the computer is capable of guessing" << endl;
cout << endl;
for(x = 0; x < words.size();x++)
{
cout << words[x]<< ", ";
}
}
Also some information on how the code is breaking, like are any errors being thrown or has debugging caused issues so far?
I've been struggling with this piece for a while now. I've googled run time check failure and I have no idea what to do. From what I get, it's because I declared swapEven and swapOdd to have an array of size 0? I initially had this set up as a pointer array, but that just didn't work. Can anybody point me in the right direction please? Thanks in advance!
void arrangeArrayJesseRagsdale(int* ary1, int* ary2, int arraySize1, int arraySize2) {
int i, j;
int temp;
int swap = 0;
int* swapEven = 0;
int* swapOdd = 0;
swapEven = new int[arraySize1];
swapOdd = new int[arraySize2];
cout << " Original Arrays\n Array #1: ";
for (i = 0; i < arraySize1; i++) {
cout << ary1[i] << " ";
}
cout << endl << " Array #2: ";
for (i = 0; i < arraySize2; i++) {
cout << ary2[i] << " ";
}
cout << endl;
for (i = 0; i < arraySize1; i++) {
for (j = 0; j < arraySize2; j++) {
if (ary1[i] % 2 != 0) {
if (ary2[j] % 2 == 0) {
temp = swapOdd[i] = ary1[i];
ary1[i] = swapEven[i] = ary2[j];
ary2[j] = temp;
swap++;
}
}
}
}
cout << "\n Updated Arrays\n Array #1: ";
for (i = 0; i < arraySize1; i++) {
cout << ary1[i] << " ";
}
cout << endl << " Array #2: ";
for (i = 0; i < arraySize2; i++) {
cout << ary2[i] << " ";
}
cout << endl;
if (swap > 0) {
cout << "\n Swapping info -\n";
for (i = 0; i < swap; i++) {
cout << " Array #1 value " << swapOdd[i] << " swapped with Array #2 value " << swapEven[i] << endl;
}
}
cout << "\nThere is/are " << swap << " swap(s)." << endl << endl;
delete[] swapEven;
delete[] swapOdd;
return;
}
First, your arrays here:
int swapEven[] = {0};
int swapOdd[] = {0};
Have 1 element each.
Second, your loops use arraySize1 and arrraySize2 to index into the arrays above. There is no check whatsoever in your code to ensure that the indexing into these arrays are within bounds. More than likely, this is where your error occurs, and that is accessing the array out-of-bounds.
If your goal is to create arrays with the same number of elements, use std::vector:
#include <vector>
//...
std::vector<int> swapEven(arraySize1, 0);
std::vector<int> swapOdd(arraySize2, 0);
The rest of the code stays the same.
swapEven and swapOdd do not have zero size, they are arrays containing the single integer element, 0. These arrays therefore have length 1.
However, from what I can tell from your code, you need to declare swapOdd to have at least as many elements as does ary1. Similarly, swapEven needs to have at least as many elements as does ary2. This is because you are storing values in those arrays using the indices of ary1 and ary2. Writing to unallocated memory may cause the crash that you see.
Also use of the indices of the 2 arrays will result in non-contiguous storage of the swapped values in swapOdd and swapEven. The affect of this is that the swap reporting code will use the wrong array elements when generating the report.
You might be better off using a dynamic "list" data structure for accumulating the swapped elements. C++ has a few alternatives there such as list and vector and these could be used instead of the swap arrays.
One other thing, rather than use pointer arithmetic to access the elements of arrays ary1 and ary2, it's more readable to use array indexing, i.e.
ary[i]
instead of
*(ary1 + i)