CODEWITHSUNDEEP
c++pointers
Andi Faust
Andi Faust

Reputation: 33

Passing a specific variable to a function and then edit the value of this variable

Well, like my title says, i want to pass a variable to a function, which ones value will then be edited in a specific way and saved again in the variable. i don't want to make the function return the computed value, i want sth. like this:

    void function(variable_name, double computing_value)
    {
     variable_name *= computing_value;
    }

for example. it'd be more comfortable for me this way. (i want to program levels for a game with it). can i do sth. with pointers to get this? like, passing a pointer to the function, and then referring to the variable the pointer points at?

Upvotes: 1

Views: 56

Answers (2)

David G
David G

Reputation: 96800

In C++ you no longer need pointers to modify a parameter. You can use a reference instead:

void function(T &t, T y) { // Where T is the type of your argument.
     t *= y;
}

In this case the parameter y will be copied, but not t. Since it is passed by reference no copy is needed; you're acting on the object itself.

Upvotes: 1

Joseph Mansfield
Joseph Mansfield

Reputation: 110658

You want a reference type:

void function(double& variable_name, double computing_value)
{
  variable_name *= computing_value;
}

Here I've assumed that variable_name should be a double. A reference type allows you to pass an argument to the function without it begin copied. That is, variable_name will be a reference to the object that was passed in.

Note: do not mistake the & in the type as the "address of" operator. It's not. They are two different meanings for & in C++. Here we are using it for a reference type.

Upvotes: 3

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