Passing para meter in the c and c++ functions

[nabakishorebehera]

hi,


I am passing a parameter as poineter in my prtotype but in the definition i am passing as reference. i am getting the warning prototype not defined.Why

Ex:

short x(byte a, short* y)//prototype of the c function
 
//Definition is 
short x(byet a, short & y)
{
    classname::x(a,y);//member function means c++ function
}
 

[Banfa]

I am passing a parameter as poineter in my prtotype but in the definition i am passing as reference. i am getting the warning prototype not defined.Why

Hi nabakishorebehera,

please make sure you use [code=cpp]...[/code] tags round your code when you post it.

Well that is because C++ supports function overloading, you have not provided the prototype for the function you have defined (that uses a reference) but you have provided a prototype for a function you have not defined.

The prototype and the definition must be exactly the same with the sole exception that in C++ (not in C) the prototype may provide default values for arguments which must not appear in the definition.


Are you trying to create a function in a CPP file that can be called from C? A fairly common technique.

To do this

1. The prototype MUST match the definition
2. Where you have the prototype in the header you must mark it as a function that uses the C naming convention, that is that does not perform then name mangling that C++ introduces to facilitate function overloading. The normal method of doing this is to inlude this code in the header file
   

   #ifdef  __cplusplus
   extern "C" {
   #endif
    
   // Prototypes for functions using C calling convention here
    
   #ifdef  __cplusplus
   }
   #endif
    

You will then be able to call the function from C or C++, the function itself may reside in a C or CPP file, if it does reside in a CPP file then even though it has C naming convention you will be able to use C++ in the body of the function, thus allowing C code to make calls into C++ code.

[gpraghuram]

hi,


I am passing a parameter as poineter in my prtotype but in the definition i am passing as reference. i am getting the warning prototype not defined.Why

Ex:

short x(byte a, short* y)//prototype of the c function
 
//Definition is 
short x(byet a, short & y)
{
    classname::x(a,y);//member function means c++ function
}
 

The function declaration and definition is not matching and thats why u are getting the error.
In C++ this becomes overloading

Raghuram