#include<stdio.h>
#include "stdafx.h"
#include<conio.h>
#include<math.h>
#include<iostream>
double a[131072];
int main(){
int count=0;
int i=0;
while(std::cin>>a[i])
{    a[i]=sqrt(a[i]);
    count++;i++;}
for(int i=count-1;i>=0;i--)
    printf("\n%.4lf",a[i]);
    getch();
    return 0;

}
it's a correct code about this program

Excuse me. Your code seems broken.
1) not working because of included headers.
2) Headers' names written in C style and C++ header
3) Using two counters. WHY, MAN, WHY.
4) Using realization-dependent headers(conio)

I present more correct one, C++.

#include <iostream>
//for cin
#include <cmath>
//for sqrt
#include <cstdio>
//for printf, replace with <iostream> if you need true cpp
// No unneeded headers.
using namespace std;
double nums[140000];
int main() {
    int x;
    for(x = 0; cin >> nums[x];x++) {;
        //Loop does everything for us. x isn't declared here because we need it outside.
    };
    //You can clearly see that only one counter is needed.
    x--;
    for(;x > -1; x--) {
        printf("%.4lf\n", sqrt(nums[x]));
        //Could use cout. How-to:
        //cout.precision(4);
        //cout << std::fixed;
        //Put them in the main(), not here.
    };
};

//Ted E. Bear saves the day. EOF.