I am trying to calculate the percentiles of a given vector of numbers, therefore i try to interpolate between the values when there is no exact percentile in the list. I tried doing the code below but when i ask the program to print with cout <<k and cout<< p[k] it does not print anything, why is it happening? What’s wrong with the code?

#include <vector>
#include <string>
#include <iostream>
#include <algorithm>

using namespace std;

vector<double> sort(vector<double>& v) {
    vector<double> copy = v;
    sort(copy.begin(), copy.end());
    return copy;
}

vector<double> percentile(vector<double>& v) {
    double t = v.size();
    double iter = 100/t;

    vector<double> c(t,0);
    for (int i = 0; i<=t; i++) {
        c[i] = iter*i;
    }

    vector <double> p(100,0);
    for (int j = 0; j<t-1; j++) {
        for (int k = c[j]; k<c[j+1]; k++) {
            if (k-c[j] == 0) {
                p[k]= v[j];
            }
            else {
                p[k] = v[j]+(v[j+1]-v[j])/(k-c[j]);
            }
            cout << k << endl;
            cout << p[k] << endl;
        }
    }

    return p;
}


int main() {
    vector<double> v {10, 12, 13, 15, 19, 22, 29, 33, 
40, 43, 32, 31, 28, 32, 45, 65, 36, 19, 20, 15};
    vector<double> v2 = sort(v);
    vector<double> p = percentile(v2);
}