INFO: Old Style (K&R) Declarations Are Not Supported in C++ (79845)

SUMMARY

The Microsoft C/C++ Compiler versions 7.0 and later do not support Old Style function declarations in C++ files. Old Style declarations are still supported in C files.

Old Style declarations, sometimes called K&R declarations, are declarations in which there are no parameters listed inside the parentheses. For example:

void KRfunc();  /* declaration */ 
void KRfunc(a, b)   /* definition */ 
int a;
char b;
{ }
				

C++ requires ANSI-style function prototypes (or declarations), which list the type of each parameter accepted by the function, as shown here:

   void ANSIfunc(int a, char b);
				

This type of declaration is required because in C++ each function has a signature. The signature consists of the name of the function and the types of the parameters it accepts. The compiler cannot construct the signature of a function from the K&R declaration.