Enum reference argument transfer instead of int reference argument

Question

I have the following code :

typedef enum {Z,O,T} num;
bool toInt (str s,int& n);//<-if convert is possible converts s to integer ,puts the result in n and returns true,else returns false

I want to use toInt function and transfer as a second argument ,argument of type num num n; toInt("2",n); This causes compilation error.

cannot convert parameter 2 from 'num' to 'int &'

I tried to use a cast : toInt("2",(num)n); But it is still problematic How can I solve the issue?

What is the compiler error? We can't help you if you don't tell us. — Pubby
– Pubby, Commented Nov 24, 2012 at 22:20
It's still fairly vague but it's probably because you need a cast. — Pubby
– Pubby, Commented Nov 24, 2012 at 22:24
I meant inside the body of the function where the parameter is being used. Except you didn't post your function body so how could I know? — Pubby
– Pubby, Commented Nov 24, 2012 at 22:30
-1: The function name is misleading. It should return int, and the matching to enum should be done outside / in other (properly named) function. — Valentin H
– Valentin H, Commented Nov 24, 2012 at 22:45

Bo Persson · Accepted Answer · 2012-11-24 22:33:23Z

1

A value of type num isn't an int, so it has to be converted to a temporary int before it is passed to the function. Tempories cannot be bound to a non-const reference.

If you want to convert via an int, you will have to convert in two steps:

int temp;
toInt("2", temp);
num n = static_cast<num>(temp);

edited Nov 24, 2012 at 22:33

answered Nov 24, 2012 at 22:26

Bo Persson

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Comments

Valentin H · Accepted Answer · 2012-11-24 22:35:01Z

1

I'd suggested, you add a new enum type for signaing invalid enum e.g:

enum num {Z,O,T,Invalid=4711} ;//no need to use typedef in C++

and change the signature to num instead of int:

bool toInt (str s, num& n)
{
 if ( s=="Z" ) n=Z; 
 else if ( s=="O" ) n=O;
 else if ( s=="T" ) n=T;
 else { n=Invalid; return false; }
 return true;
}

regards

answered Nov 24, 2012 at 22:35

Valentin H

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