Declaration for COBOL calling C++ (extern "C")

COBOL program C++ function

COBOL program	C++ function
`ID DIVISION. PROGRAM-ID. COBPROG. WORKING-STORAGE SECTION. 01 P1 PIC S9(9) USAGE IS BINARY. PROCEDURE DIVISION. CALL 'CPLUSF' USING BY VALUE P1. GOBACK.`	`extern "C" { void CPLUSF( int p1 ); } void CPLUSF( int parm ) { printf("parm=%d\n"); }`

ID DIVISION.
PROGRAM-ID. COBPROG.
WORKING-STORAGE SECTION.
01 P1 PIC S9(9) USAGE IS BINARY.
PROCEDURE DIVISION.
CALL 'CPLUSF' USING BY VALUE P1.
GOBACK.

extern "C" {
  void CPLUSF( int p1 );
}
void CPLUSF( int parm ) {
  printf("parm=%d\n");
}