调用void函数时cout没有输出

Question

I'm new to C++ so bear with me.

I am trying to create a histogram from certain parameters (interval size, length of array containing quantities of numbers, highest number yadayada).

The details are irrelevant and a problem for myself to fiddle with, although I think I got the correct formula in my function.

When I assign variables from the C++ IO "cin" I can output those with the "cout" call, however, when I call my histogram function, also containing "cout" instructions, nothing gets printed.

My code:

#include <iostream>
#include <cmath>

using namespace std;

void histogram(int l, int n, int k, int *a)
{
        int quantity = 0;
        for (int i = 1; i <= l; i++)
        {
                for (int j = 0; i < n; j++)
                {
                        if (a[j] >= (i-1) * k || a[j] <= i * k)
                        {
                                quantity++;
                        }
                }

                cout << (i-1) * k + ": " + quantity << endl;
                quantity = 0;
        }
}


int main()
{
        int l,n,k;
        int *a;

        a = new int[n];

        cin >> l >> n;

        for (int i = 0; i < n; i++)
        {
                cin >> a[i];
        }

        k = ceil((double)a[0]/l);

//      cout << k;

        histogram(l,n,k,a);

        return 0;
}

Answer 1

There might be something funky going on with this line and string concatenation: cout << (i-1) * k + ": " + quantity << endl; You might try rewriting as cout << ((i-1) * k) << ": " << quantity << endl; just to ensure that things are adding and concatenating correctly.