Programming with C language: calculate with formula: e ≈ 1+1/1+ 1/2! …+ 1/n!， Accuracy is 10-6

On the first code ：

#include<stdio.h>

void main()
{
    float f(float x);// Function declaration
    double b=1;
    float j;
    for(j=1;(1.0/f(j))>1.0e-6;j++)
    {
        b=b+1.0/f(j);
    }
    printf("%f\n",b);
}

float f(float x)
{
    float i;
    float y=1;
    for(i=1;i<=x;i++)
        y*=i;
    return y;
}

This problem uses a factorial function , Call him in the main function and guarantee the last item >10-6 To the power of