Returning more than one value???

[Matilde]

How do you return more than one value in a function? i.e. if you calculate several results and you want to reurn them...


double equation(double a = 0, double b = 0, double c = 0)
{

double sol1 = 0;
double sol2 = 0;

sol1 = (-b+sqrt((b*b)-4*a*c)/2*a;
sol2 = (-b-sqrt((b*b)-4*a*c)/2*a;

Return ????;
}

 

[MKuiper]

double equation ( double a,
                  double b,
                  double c,
                  double &sol2 )
{
  double sol1 = (-b+sqrt((b*b)-4*a*c)/2*a;
  sol2 = (-b-sqrt((b*b)-4*a*c)/2*a;
  return sol1; } 

...
 
sol1 = equation ( a, b, c, sol2 );

Marcel

 

[consistomagus]

As far as I know you cannot explicitly return more then 1 variable back through a function at a time.. You can however pass a pointer back to the variable to the function. This would allow the function to manipulate any number of variables and have their values changed by the function.

Hope that helps,
Kevin

 

[BoulderBum]

In other words, in order to "return" more than one value, (it's true more than one value cannot be returned) you must pass the additional variables by address.

( int &var1, int &var2, etc. )

in this way, a function can manipulate the variables directly, and not be limited by the single return value limitation.

 

[fheyn]

Or like this :
Use a structure inside as well as outside your function.

 

[fheyn]

additional remark (the way I learned it as good programming)

a function should always have ONE return value.

your formula (-b (+/-) sqrt(b*b-4ac)/2*a) also can give you back ONE value at a time (of course there are 2, ONE for +, ONE for MINUS)
So I think it would be better to pass an additional parameter like PLUSPART and MINUSPART and use the function
like this :

double equation(int WHICHPART,
double a = 0,
double b = 0,
double c = 0)
{
if (WHICHPART == PLUSPART)
return (-b+sqrt((b*b)-4*a*c)/2*a;
else
return (-b-sqrt((b*b)-4*a*c)/2*a;
}
and then call the function two times.

This makes your program much clearer and much more readable It sure works returning values by return and in addition throu the parameters but that's like your guests leaving the house one throu the door and the rest throu the window.

by the way : it has to be /(2*a) instead of /2*a but maybe
that's only a typing error in your poste.
and don't forget : the sqrt-part could be negative.

 

[DazzG]

If you need to return more than 1 parameter. Instead of passing pointers for individual parameters to functions it may be better to pass a pointer to a structure.

If more info is required then let me know