问无法在C程序中为循环使用外部变量值

EN

#include<stdio.h>

void main()
{
    float y= 0;
    float k = 1.0;
    float n;
    int i=0;
    int first_sqrt;
    first_sqrt = 0;

    printf("enter number: \n");
    scanf("%f",&n);

    // finding the first perfect square
    for(y = 0; y<=10000; y++)
        {
            while((k*k - n)>0.0001 || (n - k*k)> 0.0001)
            {
                k = (k + n/k) / 2;
                //printf("%f\n", k);
            }
            i = (int)k;
            if(i*i == n)
            {
                printf("perfect squareroot: %d\n", i);
                i = first_sqrt;
                y = 10001;
                //break;
            }
            else
            {
                printf("not perfect square: %f\n", n);
                n = n+1;
            }
    }
    printf("first perfect square root: %d\n", first_sqrt);
}