不用数组的方法：
#include
using namespace std;
void main()
{
int a, b, c, d;
int t;
couta>>b>>c>>d;
if(a < b)
{
t = a; a = b; b = t;
}
if(a < c )
{
t = a; a = c; c = t;
}
if (a < d)
{
t = a; a = d; d = t;
}
if( b < c)
{
t = b; b = c; c = t;
}
if (b < d)
{
t = b; b = d; d = t;
}
if (c < d)
{
t = c; c = d; d = t;
}
cout