David Ha - 6 months ago 52

C++ Question

My program runs to ask for user input of a specified integer followed by storing more integers in a dynamic array. The output gives out a histogram uses stars to show how many of each integer.

I have every task completed except for one. I have tried implementing a swap function for hours but could not figure out a solution to my problem.

My problem is that I want to get my output in order from least to greatest.

For example,

`Enter number of grades:`

5

Enter grades (each on a new line):

20

4

10

10

20

Histogram:

20 **

4 *

10 **

However, I want the following output instead

`Histogram:`

4 *

10 **

20 **

Here is my code:

`#include <iostream>`

#include <vector>

#include <algorithm>

#include <iomanip>

using namespace std;

void hist(int arr[], int n);

void swap(int &a, int &b);

int main(){

int* arr = NULL;

int number;

cout << "Enter number of grades:" << endl;

cin >> number;

cout << "Enter grades (each on a new line):" << endl;

arr = new int[number];

for(int i = 0; i < number; i++){

cin >> arr[i];

}

hist(arr, number);

return 0;

delete [] arr;

}

void hist(int arr[], int n){

cout << "Histogram:" << endl;

for (int i = 0; i < n; i++){

int j;

for (j = 0; j < i; j++)

if(arr[i] == arr[j])

break;

if (i == j){

int xx = count(arr, arr+n, arr[i]);

cout << setw(3) << arr[i] << " ";

for (int j = 0; j < xx; ++j){

cout << "*";

}

cout << endl;

}

}

}

void swap(int &a, int &b){

int temp;

temp = a;

a = b;

b = temp;

}

Answer

What you want is to sort the vector before counting the elements.

```
void hist(int arr[], int n){
sort(arr, arr+n);
...
}
```

I would suggest you to change your solution. If you were using a `std::map`

you would have the solution of your problem right there, in a preordered fashion.
Also, why don't you use a `std::vector`

?