Heapsort using Priority queue C++ - c++

Question

My code works for putting data into the array but when I print it out, it always crashes after first number. There must be something wrong with my bubbledown function, could you point out what is wrong with it? Thank you in advance.
#include<iostream>
#include <string>
#include<fstream>
using namespace std;
void bubbleup(int pq[], int back);
void bubbledown(int pq[], int front, int back);
void swap(int &a, int &b);
int main(){
ifstream infile;
ofstream outfile;
string input, output;
int size,number;
int front=1, back=0;
int *pq=new int[size]; // dynamically allocate array
cout<<"What's the input file name?"<<endl;
getline(cin, input); // get the input name
infile.open(input.c_str());// open the input file
while(!(infile.eof())){
infile>>number; // infile to an integer type variable first instead of an array. this is why your program doesn't work!!!!!
back++;
pq[back]=number;
bubbleup(pq,back);
for(int i=1;i<=back;i++)
cout<<pq[i]<<" ";
cout<<endl;
}
cout<<"what's the output file name?"<<endl;
getline(cin, output);
outfile.open(output.c_str());
while(back!=0){
cout<< pq[front]<<endl;
outfile<< pq[front]<<endl;
pq[front]=pq[back];
back--;
bubbledown(pq,front,back);
}
}
//bubbleup function
void bubbleup(int pq[], int back)
{
int fatherindex=back/2;
while(!(pq[back]>=pq[fatherindex])||!(back==1)){
if(pq[back]<pq[fatherindex])
swap(pq[back],pq[fatherindex]);
back=fatherindex;
fatherindex=back/2;
}
}
//bubbledown function
void bubbledown(int pq[], int front, int back){
int fatherindex=front,kidindex;
while(2*fatherindex+1 <= back){
kidindex=2*fatherindex+1;
if((kidindex+1<back) && (pq[kidindex]<pq[kidindex+1])){
kidindex++;
}
if(pq[fatherindex] > pq[kidindex]){
swap(pq[fatherindex],pq[kidindex]);
fatherindex=kidindex;
}
else
return;
}
}
//swap function
void swap(int &a, int &b){
int t=a;
a=b;
b=t;
}

Answer 1

A few problems to look at
You don't initialize size before using it, so your pq memory could be any size at all.
You are using 1-based access to your arrays, so make sure you allocate one more than you need.
while(!back==0) will work, but it is doing boolean logic on an int, then comparing the result with an int. while(back!=0) is a lot easier to read and will produce fewer compiler warnings.
Edit: also your bubbleDown function has an infinite loop when neither if test is triggered.