C++: pass variable by value

Question

This is the situation:

int f(int a){
    ...
    g(a);
    ...
}

void g(int a){...}

The problem is that the compiler says that there is no matching function for call to g(int&). It wants me to pass the variable by reference and g() recieves parameters by value.

How can I solve this?

What happens if you switch the definitions of f and g round? — Dominic Rodger
– Dominic Rodger, Commented Nov 7, 2009 at 18:08
Are you sure that's the right code? The function f returns an int, but there is no return statement. — Tadmas
– Tadmas, Commented Nov 7, 2009 at 18:11
Maybe your function f() doesn't know that the function g() exits. Did you forget to forward declare g()? Or switch f() and g() around like Dominic suggested. — Lucas
– Lucas, Commented Nov 7, 2009 at 18:13
Well the int& in the call doesn't mean you are required to pass a by reference. It's just showing you the arguments you passed, which are g(lvalue int). Since it cannot express lvalue-ness by means of a type, it shows g(int&) instead. — Johannes Schaub - litb
– Johannes Schaub - litb, Commented Nov 7, 2009 at 18:13

Michael Kohne · Accepted Answer · 2009-11-07 18:10:42Z

12

Well, there's not much here, but the first thing is: make sure you have a declaration for g that's included before f is defined.

void g(int a);

Otherwise, when you get to f, function f has no idea what function g looks like, and you'll run into trouble. From what you've given so far, that's the best I can say.

answered Nov 7, 2009 at 18:10

Michael Kohne

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2 Comments

Gerardo Over a year ago

yes, it is. If I declared g() as: g(int& a); it would work, but that's not what I want to do.

Lucas Over a year ago

@macaco: I think you need to post some more code then. What you have posted will not invoke any errors.

Ponting · Accepted Answer · 2009-11-07 18:13:18Z

1

Your function g() needs to be defined above f()

answered Nov 7, 2009 at 18:13

Ponting

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2 Comments

Cecil Has a Name Over a year ago

You mean declared. The compiler looks for the existence of functions, and later links to the actual implementation (the definition).

Ponting Over a year ago

yes that would also work, but if it is simple function better define it it above

Kyle Walsh · Accepted Answer · 2009-11-07 18:13:57Z

0

There are two things wrong:

1) g is not declared before it is used, so the compiler will compain about that. Assuming you fixed that issue, then the next issue is:

2) f is not returning an int.

answered Nov 7, 2009 at 18:13

Kyle Walsh

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