I’m trying to check to see how many negative numbers in an arrays and check if there’s any duplicate numbers in the same array.

Here’s the code that I’m using:

#include<stdio.h>

int main()
{
int n = 0;
int negative_count = 0;
int duplicate_count = 0;
// input lenght of the array
scanf("%d", &n);
getchar();
int arr[n];
for(int i = 0;i < n;i++){
    //input elements of the array
    scanf("%d", &arr[i]);
    getchar();
}

int len = sizeof(arr) / sizeof(arr[0]);

for(int i=0;i<len;i++){
    if(arr[i] < 0){
        negative_count++;
    }
    for(int j= i+1;j<len;j++){
        if(arr[i] == arr[j]){
            duplicate_count++;
        }
    }
}

printf("Number of negative numbers: %d\n", negative_count);
printf("Number of duplicates: %d", duplicate_count);

return 0;
}

Input

5
1 -1 2 3 -3

output

Number of negative numbers: 2
Number of duplicates: 0

the output for the negative number is correct, but the output for the duplicate is not what I wanted. It should’ve output 2 because 1 and -1 boht have the number one, and so does 3 and -3. How should I go about this?

>Solution :

If you actually want 1 and -1 to count as the same number you should use the abs() function to use the absolute value when searching for "duplicates".

abs(-1) = 1
abs(1) = 1


-1 == 1               returns false
abs(-1) == abs(1)     returns true

also remember to include <stdlib.h> to use abs()