在线等，我快疯了

#include<iostream.h>
void main(){ float a=1.0,b=1.0,c,d; do{a=a+2;
b=-b;
c=1+b*(1/a);}
while ((1/a)>=0.000001);
d=4.0*a;
cout<<d;
}

怎么输出个4E+006了呢

#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{
int a = 1;
float b = 1.0;
float c = 1.0;
do
{
a = a + 2;
b = -b;
c += b/a;
}while (a<1000000);
cout << 4*c;
system("pause");
return 0;
}

d=4.0*a;错了！

float G()
{
int a = 1;int i = 1;
float sum = 0;
for(;float(1/a)>0.0000001;a+=2,i=–i)
{
sum +=float( (1/a)*i);
}
sum *= 4;
return sum;
}