I have a child class
Code:
class IOLabel : public IOField
{
	private:
			int len;
			char format[11];
	public:
			IOLabel(int row, int col, int len); 
			IOLabel(const char *str, int row, int col);		
			~IOLabel(){};  //Deallocating non members?
			void display();
			int edit(){ 
				display();
				return 0;
			}
			IOLabel &setFormat(const char *format){ 
				strcpy(this->format,format);
				return *this;
			}
			IOLabel &operator=(const char *data){
				strncpy((char*)this->data,data,len); //Correct? Data null terminated
			}
			IOLabel &operator=(int number){ sprintf((char*)data,format,number);}
			IOLabel &operator=(double number){ sprintf((char*)data,format, number); } 
};
In my definition for one method I need to call a function written in C in the file cio.h. My professor said to use
Code:
extern "C" #include "cio.h"
but I am unsure how

Code:
void IOLabel::display(){
	extern "C"
	#include "cio.h"
	cio_display((char*)data,Row(),Col(),len);
}
Tried that but it didnt work

Code:
error C2598: linkage specification must be at global scope