#include <stdio.h>

void cat_data(int*data1, const int*data2, int len2){
	int current_len1 = 2;
	
	for (int i = 0; i < len2; i++){
		
		if (current_len1 + i >= 7){
			break;
		}
	
		*(data1 + current_len1 + i) = *(data2 + i);
	}
}

int main(void){
	
	int data1[7] = {1,2};
	int data2[5] = {3,4,5,6,7};
	
	cat_data(data1, data2, 5);
	
	for (int i = 0; i < 7; i++){
		printf("data1[%d] = %d\n", i,data1[i]);
	}
	return 0;
}