summing up array with negative number

[tt13]

Hello volks, I'm trying to write an array that add 10 integers from user's input. That will include negative numbers. My program seems fine with different test, but when I add 9 ones, and one -1, the result is 8, but the answer supposed to be 9.
(What I tested to Enter 1 1 1 1 1 1 1 1 1 -1, result =8). Please point out my error! Thank you

#include <iostream>
using namespace std; 
int main(){
	
	int array1[9];
	int sum=0;
	int count=0;
	
	
	cout <<"Enter 10 interger numbers: " <<endl;
	
	for(int i=0; i<=9; i++){
		cin>> array1[i];
		sum+= array1[i];
	}
	
	cout <<"The sum of the interger numbers is: " << sum <<endl;
	
	for (int i=0; i<=9; i++){
		if(array1[i]<0){
			count ++;
		}
	}
	cout <<"You've entered: " <<count << " of negative number(s)";
	
	
	
	
	
	return 0;
}

[gunnerfunner]

when I add 9 ones, and one -1, the result is 8, but the answer supposed to be 9.

i haven't checked your program but the result of 9*1 - (1) should indeed be 8, not 9

[tt13]

OMG, that's right I did a stupid calculation, LOL, thank you!