Piece of code doesn't give the answer I need. Suggested edits? - c++

Question

This code is supposed to check the input array for five consecutive '1's if found, it is supposed to add a '0' at the end as a parity bit for a simple parity bit checker.
This is the code.
#include <conio.h>
#include <stdio.h>
#include <iostream>
using namespace std;
int main() {
int n, a[30], b[5] = {1, 1, 1, 1, 1}, temp = 0, count = 0;
cout << "Enter the size of input bits :";
cin >> n;
cout << endl;
cout << "Enter the input bits :";
for (int i = 0; i < n; i++) {
cin >> a[i];
}
for (int i = n; i >= 0; i--) {
if (i >= 4) {
temp = i;
for (int j = 0; j < 5; j++) {
if (a[temp] == b[j]) {
temp++;
count++;
}
}
}
}
if (count == 4) {
n = n + 1;
a[n] = 0;
}
cout << endl << endl;
for (int i = 0; i < n; i++) {
cout << a[i];
}
getch();
return 0;
}

Answer 1

Here is a simple logic of what you want to achieve.. let's say input array is a, it's length is n:
int counter = 0;
for(int i=0; i<n; i++) {
if(a[i] == 1)
counter++;
else
counter = 0; //need to start looking for 1's again because consecutive stream is broken
if(counter == 5) {
a[i+1] = 0; //found 5 consecutive 1's so next bit will be 0
i++; //don't need to check the next bit which is already 0
counter = 0; //resetting counter
}
}
The above code will change the array [2,3,1,1,1,1,1,3,4,5] to -> [2,3,1,1,1,1,1,0,4,5]
If you want to insert 0 at the end of the array then simply change a[i+1] = 0 to a[n+1] = 0 and remove i++;
You also need to make sure that n is not greater than the size of array.

Answer 2

I'll go line by line from the beginning:
change for(int i=n; i>=0; i--) to for (int i = n-1; i >= 0; i--) (n-sized array in C++ has cells in the range of [0, n-1])
change if(i>=4) to if (n >= 5)
place temp++ after if(a[temp]==b[j]){}, not inside of it.
add
if (count == 5) break;
else count = 0;
just after for(int j = 0; j < 5; j++) loop
change
if(count==4)
{
n=n+1;
a[n]=0;
}
to
if(count == 5){
a[n] = 0;
n = n+1;
}
Once again! n-sized array holds n elements on positions 0 to n-1
Of course sequence makes a difference above!
You can also write it as if (count == 5) a[n++] = 0;
And that would be all.