C Caller does not show port specification?

Hello,

as You can see C caller does not show Port specification of the c code of the MatLab video shown here:https://www.youtube.com/watch?v=ONrb_UYTWYs&ab_channel=MATLAB

#ifndef HEADER_H_
#define HEADER_H_

// Global Variable

extern double gVec[5];
extern double sum;


//Function
extern void cumulativeAdder(void);

#endif
   

source code

#include "header.h"


double gVec[5];
double sum = 0;

void cumulativeAdder(void){
	int idx = 0, tmpSum = 0;
	
	for(; idx < 5, ++idx){
		tmpSum = tmpSum + gVec[idx);  // Function reads "gVec" as INPUT
		}
		
	sum = tmpSum; //Function writes to "sum" as OUTPUT
	
}