This question already has answers here:
How to implement 2D vector array?
(9 answers)
How do I declare a 2d array in C++ using new?
(29 answers)
Closed 1 year ago.
I'm trying to pass a 2D array into a function with the user's input (asking the user for the number of columns, rows, etc. Here's the code I have. Is there a way to pass the function with said inputs?
#include <iostream> // Input and output
#include <iomanip> // Input manipulator
#include <array>
using namespace std;
int rows;
int columns;
int getTotal(int array[][columns], int, int);
int main()
{
cout << "How many rows would you like to have in your array? " << endl;
cin >> rows;
cout << "How many rows would you like to have in your array? " << endl;
cin >> columns;
int userArray[rows][columns];
getTotal(userArray, rows, columns); // This column will not call the function
return 0;
}
int getTotal(int userArray[][columns], int rows, int columns)
{
// function to add all numbers
}
Related
This question already has answers here:
C++ : Creating an array with a size entered by the user
(3 answers)
Closed 1 year ago.
How can I take array input of any size? I tried doing with this code but don't know where the error is. Please Help me Out
#include <iostream>
using namespace std;
int main()
{
int arr[10000];
int i;
int arrSize = sizeof(arr)/sizeof(arr[0]);
if(i=0; i<arrSize; i++)
{
cin>>arr[i];
}
cout << "The size of the array is: " << arrSize;
return 0;
}
Try using for instead of if. Also, no need to do that sizeof thing. Just put the size of the array there or take the number of elements as an input from the user.
This question already has answers here:
How to find the size of an array (from a pointer pointing to the first element array)?
(17 answers)
C sizeof a passed array [duplicate]
(7 answers)
Closed 4 years ago.
I'm facing some problems with my code in C++. I would like to know how can I discover the amount of elements in an array. Follow the code:
#include <iostream>
#include <cstdlib>
using namespace std;
int avg(int numbers[]){
int amount; // The problem is in. How can I discover the amount of elements in an array?
int sum = 0;
for(int i = 0; i < amount; i++){
sum += numbers[i];
}
return sum / amount;
}
int main(){
int q;
cout << "Type number of integers:" << endl;
cin >> q;
int numbers[q];
for(int i = 0; i < q; i++){
cout << "Type an integer value for number " << i+1 << ":" << endl;
cin >> numbers[i];
}
cout << "The average is " << avg(numbers) << endl;
return 0;
}
The standard array in C++ doesn't contain a way to access the size of the array, the best way to track this is to have an integer that is updated with the size of the array or to try using std::array and then use the .size() method.
In your example you are using a fixed size array anyway so you may want to store the q value as a member variable and that contains the array size. Notice that in your example the code will not work as q is not a constant integer. To declare an array without a constant integer you will need to use a pointer to the first element of the array ie: int* numbers = new int[q];.
I am attempting to create a two dimensional array depending on the users desired number of rows and columns. I am receiving an error of "use of undeclared identifier 'rows'". I googled and searched on stack overflow but was not able to find a scenario like this, I would like to know what am I doing wrong below is my code :
#include <iostream>
using namespace std;
class Matrix{
public:
int matrixDimensions[rows][columns];
void setMatrix(int x, int y){
rows = x;
columns = y;
}
int getMatrixDimensions(){
return rows;
return columns;
}
private:
int rows;
int columns;
};
int main(int argc, const char * argv[]) {
int a;
int b;
Matrix matrixObject;
cout << "Please enter the number of rows: " << endl;
cin >> a;
cout << "Please enter the number of columns: "<< endl;
cin >> b;
matrixObject.setMatrix(a, b);
cout << "The number of rows and columns are : " << matrixObject.getMatrixDimensions();
return 0;
}
Thank you all feedback is welcomed.I cannot use vectors, thank you for mentioning them but it is not an option here.
In C++, if you want to declare an array regardless of dimension, you can only declare it before the compile time.
For example, let SIZE be the user input during run time
int arr[5] // OK
int arr[SIZE] // NOT OK
If you want to dynamically allocated the array size during the run time, you have to use the pointer.
int* arr = new int [5] // OK
int* arr = new int [SIZE] // OK
Take a look in
How do I declare a 2d array in C++ using new?
Try declaring the variables rows and columns before the functions. C++ will check the syntax line by line. So it might be the issue.
This question already has answers here:
getting size of array from pointer c++
(6 answers)
Closed 7 years ago.
Alright so this is probably a really simple question, I'm just really new to c++ and am struggling to understand most things. I've been asked to create an array that stores random numbers but the user is to define the size of the array. I then have to display all the numbers in the array. What I'm struggling with is displaying all elements of the array. At the moment, I'm pretty sure I've got the array part down, but I can only seem to display one number. Here's my code so far:
#include <iostream>
#include <cstdlib>
#include <stdlib.h>
#include <ctime>
using namespace std;
using std::srand;
using std::rand;
using std::time;
void Display(int *, int);
int main(void)
{
int userSize;
cout << "Please enter the size of the array: ";
cin >> userSize;
int* randArray = new int[userSize];
srand(time(NULL));
for (int i = 0; i < userSize; i++) {
randArray[i] = rand() % 20 + 1;
}
//Disregard the next few lines, I was just testing to see if anything was actually in the array.
/*cout << randArray[0] << endl;
cout << randArray[1] << endl;
cout << randArray[2] << endl;
cout << randArray[19] << endl;*/
Display(randArray, sizeof(randArray) / sizeof(int));
return 0;
delete[] randArray;
}
void Display(int *arrayData, int numElements)
{
for (int counter = 0; counter < numElements; counter++)
{
std::cout << *(arrayData + counter) << std::endl;
}
return;
}
I should also mention that the teacher provided us with the code after the line that deletes the array.
This is the question I have to answer: Ask the user for the number of elements to be stored in the array. You should then dynamically allocate the memory to hold this array, which will proceed to be used in the same way as the previous task (populating the array with random data, displaying the data to the
screen).
sizeof(randArray) does not tell you the number of bytes that you've allocated. Rather, it tells you the size of a pointer, which on your system happens to be the same as the size of an integer, so sizeof(randArray) / sizeof(int) returns 1 always. Instead use userSize as your second parameter in the function call to Display.
Also, you delete[] randArray after return 0. This is incorrect; nothing after the return 0 will be executed. You want it above instead.
Further, consider the use of std::vector instead (unless you are required to use a raw pointer for this assignment)
The problem is sizeof. It gives you the size of the type of the argument, not of what is behind. Your should pass userSize to Display().
You should also delete the array before you return. Code behind return never gets executed.
This question already has answers here:
Array size at run time without dynamic allocation is allowed? [duplicate]
(8 answers)
Closed 7 years ago.
I receive these errors
1. cannot allocate an array of constant size 0
2. expected constant expression
3. 'numbers' : unknown size
#include <iostream>
#include <string>
using namespace std;
int main()
{
string str;
int input_num;
int sum;
cout << "Enter the number:" << endl;
getline(cin, str);
const int length = str.length();
cout << "Length:" << length<<endl;
//input_num = stoi(str);
int numbers[length];
return 0;
}
Replace the use of an array by a std::vector, and initialize the elements to 0.
std::vector<int> numbers(length, 0);
The size of an array has to be a constant expression greater than 0.
You should use standard class std::vector<int> instead.
For example
#include <vector>
//...
std::vector<int> numbers( length );
If the user has to enter a number of type for example int (that is the number might be in the range of acceptable values of object of type int) then you could define the array beforehand the following way
#include <limits>
//...
int numbers[std::limits<int>::digits10 + 1];