help me

[miladam]

hi,i write this program to sort 7 numbers,tell me my mistake.

  #include <iostream>

using namespace std;
void milad(double * a,double * b)
{
    if (a<b)
    {
        double * c;
        *c=*a;
       * a=* b;
       * b=* c;
    }
}
int main()
{
    int i,j;
    double a[7];
    for(i=0;i<7;i++)
    {cin>>a[i];}
    for(i=0;i<7;i++)
    {
        for(j=i;j<7;j++)
        milad(&a[i],&a[j]);
    }
    for(i=0;i<7;i++)
    {
        cout<<a[i];
    }
    return 0;
}

[mutexe]

one thing that immediately sticks out (but there's more stuff wrong I reckon) is

if (a<b)

you are comparing the pointers, not the values that they hold.

[miladam]

ok,i fix this error but this program have runtime error,why?

[mutexe]

line 19 makes no sense.

what are you trying to achieve? It looks like you are trying to do a strange mix of populating your array and getting user input.

[mutexe]

you also don't initialise your 'c' pointer inside your milad() function.

[MikeyBoy]

In fact, why does c need to be a pointer at all?

[mutexe]

in fact, why any pointers at all?

int main()
{
	double a[7];

	// some test data
	a[0] = 4;
	a[1] = 2;
	a[2] = 11;
	a[3] = 65;
	a[4] = 12;
	a[5] = 76;
	a[6] = 1;

	bool bSwapped(true);
	double temp(-1);

	for(int i = 1; (i <= 7) && bSwapped; i++)
	{
		bSwapped = false;
		for (int j=0; j < (7 -1); j++)
		{
			if (a[j+1] < a[j])    
			{ 
				temp = a[j];          
				a[j] = a[j+1];
				a[j+1] = temp;
				bSwapped = true;              
			}
		}
	}


	//  display array elements here.
	return 0;
}

[ngbeslhang]

Seriously, why use double instead of int?

[MikeyBoy]

Seriously, why use double instead of int?

Erm... presumably because the OP wanted to sort floating-point numbers, rather than integers?

I fail to see how it makes any difference to solving the problem. The solution would be no different for ints.