#include<stdio.h>
#include<conio.h>
#include<math.h>
#define MAX 100

void nhap (int a[], int &n)
{
	do
	{
		printf("\nNhap so phan tu: ");
		scanf("%d", &n);
		if(n <= 0 || n > MAX)
		{
			printf("\nSo phan tu khong hop le. Xin kiem tra lai !");
		}
	}while(n <= 0 || n > MAX);
	for(int i = 0; i < n; i++)
	{
		printf("\nNhap a[%d]: ", i);
		scanf("%d", &a[i]);
	}
}

void xuat(int a[], int n)
{
	for(int i = 0; i < n; i++)
	{
		printf("%4d", a[i]);
	}
}

int KiemTraChuSoDauChan(int n)
{
	while(n >= 10)
	{
		n /= 10;
	}
	if(n % 2 == 0)
	{
		return 1;
	}
	return 0;
}

int TinhTongCacSoChuSoDauChan(int a[], int n)
{
	int Tong = 0;
	for(int i = 0; i < n; i++)
	{
		if(KiemTraChuSoDauChan(a[i]) == 1)
		{
			Tong += a[i];
		}
	}
	return Tong;
}
int main()
{
	int n;
	int a[MAX];

	nhap(a, n);
	xuat(a, n);
	int tong = TinhTongCacSoChuSoDauChan(a, n);
	printf("\nTong cac so co chu so dau chan = %d", tong);

	getch();
	return 0;
}

Line 17: error: conio.h: No such file or directory
Line 6: error: expected ';', ',' or ')' before '&' token
In function 'xuat':
Line 26: error: 'for' loop initial declaration used outside C99 mode
In function 'TinhTongCacSoChuSoDauChan':
Line 48: error: 'for' loop initial declaration used outside C99 mode